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The Third International Conference on the Development of Biomedical Engineering in Vietnam pp 10–13 Cite as

Ultrasound: Past, Present and Future

  • K. Kirk Shung 4  
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Ultrasound has been used as a diagnostic tool for more than 40 years. Many medical applications have been found, mostly notably in obstetrics and cardiology. It had a humble beginning, started by a few curious scientists and clinicians in different parts of the world in early 1950s and did not become an established diagnostic tool until early 1970s when grey scale ultrasonography was introduced. Modern ultrasound scanners are capable of producing images of anatomical structures in great detail in grey scale and of blood flow in a color scale in real-time. State of the art 4D scanners yielding 3D volumetric images in real-time are pushing the technical envelope further. Today ultrasound is the second-most used clinical imaging modality next only to conventional x-ray radiography. Although ultrasound is considered to be a mature technology, technical advances are still constantly being made. The most significant achievements in ultrasound recently have been in the developments of approaches capable of quantitative measurement of tissue elastic properties, namely ultrasound elastography and radiation force imaging, high frequency imaging yielding improved spatial resolution and therapeutic applications in drug delivery and high intensity focused ultrasound surgery. In this paper, the history and current state of medical ultrasound will be reviewed and future developments discussed.

  • ultrasonic imaging
  • color Doppler
  • elastography
  • radiation force imaging

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Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA

K. Kirk Shung

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Chair of Biomedical Engineering Department, International University - Vietnam National, Universities at HCM, Quarter 6, Linh Trung, Thu Duc Dist., Ho Chi Minh City, Vietnam

Biomedical Engineering Department, International University - Vietnam National Universities at HCM, Quarter 6, Linh Trung, Thu Duc Dist., Ho Chi Minh City, Vietnam

Truong Quang Dang Khoa

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Shung, K.K. (2010). Ultrasound: Past, Present and Future. In: Van Toi, V., Khoa, T.Q.D. (eds) The Third International Conference on the Development of Biomedical Engineering in Vietnam. IFMBE Proceedings, vol 27. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-12020-6_3

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  • Published: 19 November 2019

Point-of-care ultrasound in primary care: a systematic review of generalist performed point-of-care ultrasound in unselected populations

  • Bjarte Sorensen   ORCID: orcid.org/0000-0002-6328-0869 1 &
  • Steinar Hunskaar 2 , 3  

The Ultrasound Journal volume  11 , Article number:  31 ( 2019 ) Cite this article

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Both the interest and actual extent of use of point-of-care ultrasound, PoCUS, among general practitioners or family physicians are increasing and training is also increasingly implemented in residency programs. However, the amount of research within the field is still rather limited compared to what is seen within other specialties in which it has become more established, such as in the specialty of emergency medicine. An assumption is made that what is relevant for emergency medicine physicians and their populations is also relevant to the general practitioner, as both groups are generalists working in unselected populations. This systematic review aims to examine the extent of use and to identify clinical studies on the use of PoCUS by either general practitioners or emergency physicians on indications that are relevant for the former, both in their daily practice and in out-of-hours services.

Systematic searches were done in PubMed/MEDLINE using terms related to general practice, emergency medicine, and ultrasound.

On the extent of use, we identified 19 articles, as well as 26 meta-analyses and 168 primary studies on the clinical use of PoCUS. We found variable, but generally low, use among general practitioners, while it seems to be thoroughly established in emergency medicine in North America, and increasingly also in the rest of the world. In terms of clinical studies, most were on diagnostic accuracy, and most organ systems were studied; the heart, lungs/thorax, vessels, abdominal and pelvic organs, obstetric ultrasound, the eye, soft tissue, and the musculoskeletal system. The studies found in general either high sensitivity or high specificity for the particular test studied, and in some cases high total accuracy and superiority to other established diagnostic imaging modalities. PoCUS also showed faster time to diagnosis and change in management in some studies.

Our review shows that generalists can, given a certain level of pre-test probability, safely use PoCUS in a wide range of clinical settings to aid diagnosis and better the care of their patients.

Point-of-care ultrasound, PoCUS, can be defined as the use of an image-producing ultrasound device for diagnostic and procedural guidance, by the clinician himself, at the point of care, in real time allowing for direct correlation with signs and symptoms [ 1 ]. It is integrated in the clinical work, and may increase accuracy of diagnoses or aid procedures, as well as reduce time spent to diagnoses and decreased overall costs [ 2 ].

General practitioners (GPs), or family physicians, work in a range of settings and levels of urgencies, from daytime run clinics, through out-of-hours (OOH) services such as primary care urgent care centres, to the provision of undifferentiated emergency medicine in rural and remote regions. Globally, there are many different organisational models for OOH services, often running in parallel, including GP rota groups, cooperatives, primary care centres, as well as in-hospital emergency departments [ 3 ].

General practitioners are trained to manage both chronic conditions as well as acute emergencies, often within the same session, seeing women and men, young and old. In many countries, such as Australia [ 4 ] and Canada [ 5 ], general practitioners in rural and remote areas are expected to handle all emergencies and are often the only physicians available for initial diagnosis, management, and stabilisation within several hours of travel by road, water, or air. In countries such as Norway [ 6 ] and New Zealand [ 7 ], GPs are organised as part of the emergency response chain acting as a first responder and a team member to the ambulance services. Skills such as obtaining peripheral venous access and diagnosing life-threatening medical and traumatological conditions are expected [ 8 , 9 ].

There are, therefore, many settings where the GP could potentially benefit from her own use of PoCUS. Both the interest and actual extent of use among GPs are increasing and PoCUS training is also increasingly implemented in residency programs [ 10 ]. However, the amount of research on PoCUS performed by GPs is still rather limited compared to other specialties in which it has become more established, such as in the specialty of emergency medicine [ 11 , 12 ].

A recently published systematic review of PoCUS in general practice, identifying articles where the operators were GPs, concluded that it has the potential to be an important tool for the GP and possibly reduce health costs, but emphasises the need for further research [ 12 ]. Meanwhile, we think that it may be useful to also review studies where the setting is similar and the PoCUS operators also are, like GPs, physicians with a generalist training and perspective. We made the assumption that findings from studies where the operator is an emergency physician (EP) working in an unselected emergency department population also will be relevant for GPs.

The aim of this systematic review is thus twofold: first, to examine the extent of use among both GPs and EPs; second, to identify primary clinical research articles or meta-analyses on PoCUS for indications relevant for GPs in which the population is unselected (open GP practice or emergency departments) and the operators are either GPs or EPs.

Systematic searches were performed in the PubMed databases. Indexed MEDLINE-articles were identified by medical subject headings’ (MeSH) keywords describing ultrasound, general practice, and emergency medicine (Table  1 ). Non-indexed PubMed articles were identified by corresponding keywords (Appendix 2 shows the exact search algorithm). The reference lists of included articles were also reviewed.

Only studies involving the clinical use of two-dimensional image-producing ultrasound at the point of care were included. Studies on hospitalised inpatients were excluded, as well as studies where the operator was a non-generalist, non-physician, or prehospital emergency medical service personnel. Case studies or case series were excluded, as were the use of ultrasound on hyperacute indications or for procedures less likely to be of relevance to most general practitioners (Appendix 1 ). Meta-analyses where the majority of the included articles fit our inclusion criteria were included, and the individual studies analyzed by these meta-analyses were excluded from our review to avoid double treatment. Articles published after the latest meta-analyses were included, as were articles outside the scope of the meta-analyses identified. Articles in other languages than English, German, Spanish, or any of the Scandinavian languages were excluded. The search was last performed on 1 June 2019.

We identified 15,745 articles which were screened for eligibility, and after screening, 1413 full text articles we were left with 213 articles for inclusion, as shown in Fig.  1 . Out of these, 19 were articles about the extent of use, while 26 were meta-analyses, and 168 primary research studies on PoCUS.

figure 1

Study selection flow diagram

The extent of use

There is great variation in the extent of use of PoCUS among GPs in Europe. In Norway, 23% of emergency primary care centres had access to their own ultrasound machines in 2015. However, only 1 of 15 of the GPs working there used ultrasound ever and only 0.3% of billings included an ultrasound item [ 13 ]. Ultrasound was in 2014 commonly used in Germany (about 45%) and Greenland (about two-thirds), while it was less commonly used in Sweden, Denmark, Austria, and Catalonia (< 1%) [ 14 ]. GPs, and EPs, working in emergency departments in rural Canada had good access to ultrasound equipment already in 2013 and increasingly until today (60–95%), while between 44 and 76% reported, they used ultrasound, a third of these on every shift [ 15 , 16 , 17 ].

Among EPs, ultrasound was used in 5% of the consultations in emergency departments in France in 2014 [ 18 ]. French emergency departments (EDs) have seen an increase in the availability of ultrasound equipment from 52 to 71% between 2011 and 2016 [ 19 ]. EPs had access to ultrasound equipment in 89% of Danish emergency departments in 2013 [ 20 ]. In China, 54% of EPs reported having access to equipment in 2016, and 43% of respondents reported using PoCUS in their clinical work [ 21 ]. In South Korea, it was available in 2014 in all surveyed EDs and 82.7% of respondents used PoCUS daily on adult patients, but only 23.6% performed paediatric PoCUS daily [ 22 ]. In Colombia, 57% of all emergency medicine residents responded that they lacked equipment, while 52% responded that they had used ultrasound during their training [ 23 ]. The use of PoCUS is integrated in the emergency physician training in the USA [ 24 ], and from 2004 to 2015, the access to equipment in emergency departments has risen from 19% to between 66 and 96%, and the lack of physician training is now seen as the major barrier rather than the lack of available technology [ 25 , 26 , 27 , 28 , 29 , 30 ].

Relevant indications

We found 26 meta-analyses and 168 primary studies on PoCUS used by generalists on a wide range of indications that we deemed relevant for the general practitioner, and they have been sorted according to the relevant organ systems: heart, lungs, vessels, abdomen, obstetric ultrasound, the eye; soft tissue, and musculoskeletal system.

The most studied parameter was diagnostic accuracy, and Tables  2 , 3 , 4 , 5 , 6 , 7 and 8 show the test characteristics of a multitude of examinations. The sensitivities and specificities are displayed, and 95% confidence intervals are included where available. Positive and negative likelihood ratios (LR+/LR−) have been listed rather than positive and negative predictive values, as the former are prevalence independent, while the latter is only valid for the given prevalence in the studied population. Where either of the tabulated parameters was not available, we calculated these from the given data and indicated as such in the tables. Where available, the amount of time spent on specific didactic teaching is listed.

To the extent any other parameters than diagnostic accuracy were studied, this is presented narratively in the below text.

Studies on indications relating to the heart are summarized in Table  2 . Even though a GP in a Norwegian pilot study from 1985 concluded that “echocardiography will not have any diagnostic significance in general practice in the foreseeable future” [ 31 ], a similar UK study was more positive in 1998 where one found GP performed evaluation of left-ventricular function frequently altered management [ 32 ].

Three studies from the last few years evaluated GPs’ use of echocardiography compared to cardiologist as the reference, all of which found that, after 4–28 h of instruction, the GP could assess left-ventricular form and function with an accuracy high enough to impact management [ 33 , 34 , 35 ]. GPs have been found to reliably measure the mitral annular plane systolic excursion (MAPSE) through the use of pocket ultrasound after an 8 h teaching program with a sensitivity of 83% and a specificity of 78% [ 33 ]. A Spanish study found high accuracy for detecting left-ventricular hypertrophy (LVH) with GP operated pocket ultrasound in hypertensive patients in general practice, with a LR+ of 56 and a LR− of 0.1 [ 34 ]. They also found clinically useful test accuracy for other abnormalities. Another Spanish study found that GPs using pocket echocardiography on several indications had a very high specificity (93–100%) for a range of diagnoses, including LVH and valvular pathologies, but a rather low sensitivity (41–72%) [ 35 ].

Nine studies showed that EPs of varying experience could estimate left-ventricular ejection fraction (LVEF) and showed an overall agreement with cardiologists of between 84 and 93%, both on visual estimation and calculated values using, e.g., E-point septal separation [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. Another study showed good agreement between EPs and cardiac sonographers on obtaining windows for left-ventricular outflow tract for velocity time integral studies [ 45 ], and it has been shown that EPs were able to obtain those windows for more than half of their ED patients [ 46 ]. Three studies identified high sensitivities and moderate-to-very good agreement with cardiologists for detection of diastolic dysfunction [ 47 , 48 , 49 ], while an Italian study found a high correlation between EP findings of restrictive mitral pattern and the presence of left-ventricular heart failure, with an LR+ of 8.27 [ 50 ]. EPs have also been shown to have good inter-rater agreement for the assessment of overall diastolic function [ 51 ].

Emergency physicians ability to detect wall motion abnormalities showed very good agreement with cardiologists in two studies [ 43 , 52 ], while a 2018 US study sought to find whether EPs could use speckle tracking software to identify wall motion abnormalities and found that the sensitivity was low at 29%, but specificity high at 88% [ 53 ].

The ability to detect pericardial fluid by EPs was studied in four studies which all found sensitivities from 60 to 96% and specificities from 96 to 100% despite short training periods. False-negative findings were more likely for smaller effusions [ 39 , 42 , 43 , 54 ].

Findings from studies on lung ultrasound are detailed in Table  3 . Lung ultrasound (LUS) can be used to detect diffuse interstitial syndrome (bilateral B lines), which, in the setting of suspected acute decompensated heart failure (ADHF), likely signifies pulmonary oedema. We identified five meta-analyses on this utility of LUS in the emergency department, all concluding that both the sensitivity and specificity are very high [ 55 , 56 , 57 , 58 , 59 ], and indeed the one test with the best test characteristics compared to all other clinical parameters for ADHF ever studied [ 55 ]. One meta-analysis only included studies where also chest X-ray (CXR) had been compared with LUS towards the same gold standard, and found that CXR had the same specificity (90%) but lower sensitivity than LUS (73% vs 88%) [ 58 ]. A recent randomised-controlled study by Pivetta et al. [ 60 ], not analyzed in these meta-analyses, allocated patients after the initial suspicion of ADHF into groups receiving CXR and pro-brain natriuretic peptide (pro-BNP) or LUS, and found not only that LUS had both superior specificity and sensitivity compared to the criterion standard of final chart diagnosis, but also a shorter time to the diagnosis (5 min vs 104.5 min). Finally, one Australian study analyzed inter-rater agreement between experienced and novice EP lung sonographers which was found to be good, with a Cohen’s kappa coefficient of 0.70 [ 61 ].

Three meta-analyses were identified that assessed the accuracy of LUS in diagnosing pneumonia in unselected adult populations [ 59 , 62 , 63 ]. Orso et al. found 17 studies in ED populations where focal subpleural consolidations, focal B lines, or a combination of these were considered a positive finding, using X-ray and/or CT as the criterion standard, and found a pooled sensitivity of 92% and a specificity of 93%, similar to the findings in the meta-analysis by Staub et al. [ 59 ]. Ye et al. [ 63 ] only included studies where LUS was directly compared to CXR using the final diagnosis as the criterion standard, and found that LUS had a sensitivity of 95% against 77% for CXR, while the specificity was the same, 90%. A recent study not included in these meta-analyses found a similar superiority to CXR in a Nepalese ED population [ 64 ].

An Italian study on PoCUS for pneumonia in a paediatric population by one expert EP ( n  = 79) agreed with the final diagnosis of pneumonia in all cases and had no false-positive findings [ 65 ]. A later study in 200 children with suspected pneumonia (prevalence = 18%) showed sensitivity and specificity of 86% and 89%, respectively, when compared to CXR as the gold standard [ 66 ]. Ultrasound has been shown to be more sensitive than CXR in a study of a paediatric ED population, but less specific [ 67 ], and another study showed a 39% reduction in use of CXR for the final diagnosis of pneumonia in children in a randomised trial, with no cases of missed diagnoses or complications [ 68 ]. PoCUS by paediatric EPs instead of CXR was in one study associated with less time spent and decreased overall costs [ 69 ].

The absence of pleural sliding and B lines is a sign of pneumothorax, and finding the point where the pleural layers separates from each other, the lung point, is pathognomonic. A recent meta-analysis showed a very high accuracy of PoCUS when performed by EPs, with 88% sensitivity and 99% specificity, and it was superior to CXR which had 46% sensitivity and 100% specificity [ 70 ]. The findings were similar in another recent meta-analysis, albeit with a somewhat heterogeneous operator group [ 71 ], as well as in a recent original prospective observational study [ 72 ].

Two studies from 2017 used the total cases of positive findings of rib fractures found by either LUS or CXR as the criterion standard (assuming that there were no false-positive findings) and found a sensitivity of 81–98% in LUS compared to 41–53% for CXR [ 73 , 74 ]. A third study found a similar concordance between LUS and CXR and/or CCT [ 72 ].

Two studies evaluated the accuracy of PoCUS through present lung sliding and predominant A lines as a marker for asthma or chronic obstructive pulmonary disease (COPD) in the setting of dyspnoea, and found an LR+ of 3.8–6.3 and an LR− of 0.05–0.40 [ 75 , 76 ]. Such LUS findings can also be seen in patients without pulmonary pathology, which may explain the poorer test characteristics seen in the undifferentiated ED populations compared to what has been seen in intensive-care unit populations [ 59 ].

Finally, we identified 11 articles which studied the impact of different PoCUS protocols on the overall diagnosis of patients presenting with undifferentiated respiratory or chest symptoms. An Italian ED-based study showed that LUS in the setting of pleuritic pain without dyspnoea had 97% sensitivity and 96% specificity for detecting lesions that did not show up on CXR, using other imaging modalities and final diagnosis as their criterion standard [ 77 ]. Another Italian study found that LUS in dyspnoeic patients changed the diagnosis in 44% of cases and altered management in 58% [ 78 ]. Danish EPs evaluating dyspnoeic patients with PoCUS of heart, lung, and deep veins found life-threatening diagnoses that were missed in the primary assessment in 14% of patients, reporting a total of 100% sensitivity and 93% specificity for the diagnosis of such conditions [ 79 ]. The same group randomised 320 dyspnoeic patients (and SpO2 < 95%) into a PoCUS group or management as usual, and found as their primary endpoint a significant 24% higher accuracy in diagnosis at 4 h (88% vs 64%), using masked audit as the gold standard [ 80 ]. Similarly, two studies found a significant reduction in time needed for diagnosis using integrated ultrasound on dyspnoeic patients [ 81 , 82 ]. It has also been shown that the addition of heart and lung PoCUS allowed the EPs to reduce the number of diagnoses on their differential diagnosis list from 5 to 3 ( p  < 0.001) [ 83 ], and also three other studies showed statistical significance in PoCUS overall diagnostic accuracy in patients with dyspnoea [ 84 , 85 , 86 ]. One USA study could not show significant diagnostic or management changes when a PoCUS protocol was applied to dyspnoeic patients in ED significantly, but it improved EPs’ confidence levels [ 87 ].

Main test characteristic findings can be found in Table  4 .

Screening for abdominal aortic aneurysms (AAA) by GPs would require a very high accuracy to avoid false positive in a relatively low pre-test probability population, even if one selects the population who is at risk, men who have smoked in the ages between 65 and 75. We identified three small studies of GPs’ screening for AAA in such populations against a gold standard [ 88 , 89 , 90 ]. All found 100% accuracy for AAA greater than 3 cm and concluded screening by GPs were feasible. One larger feasibility study only confirmed positive cases [ 91 ]. Hoffmann et al. [ 92 ] also found screening by EPs in the emergency department feasible, but requiring substantial resources for a low success rate.

In a Danish study, inexperienced GPs achieved 100% accuracy for AAA > 5 cm compared to radiologists when the scan was performed on clinical indication [ 93 ]. Similarly, one meta-analysis showed that EPs have very high accuracy for detecting AAA > 3 cm compared to formal radiologist performed ultrasound when performed on indication [ 94 ].

One Japanese retrospective study investigated the impact of GPs screening of carotid intima media thickness in patients at risk of coronary artery disease (CAD) on later interventions, and found an increase in the prevalence of CAD in patients referred to a local specialist centre and higher probability of coronary angiograms and revascularization [ 95 ].

One multi-centre study assessed Italian GPs’ accuracy of a two-point compression technique for the identification of lower extremity deep vein thrombosis (DVT) and found 90% sensitivity and 97% specificity compared to radiologist ultrasound [ 96 ]. A meta-analysis on EPs use of PoCUS for detection of DVT found even higher accuracy with a sensitivity of 96% and a specificity of 97% [ 97 ]. A newer meta-analysis from 2019 shows a pooled sensitivity of 91% and a specificity of 98% for the two-point compression technique (assessing the common femoral vein and the popliteal vein) and similarly 90% and 95% for the three-point compression technique (including the superficial femoral vein) [ 98 ]. Three other studies not analyzed in above meta-analyses show similar test accuracies [ 99 , 100 , 101 ]. One study showed a > 4-fold reduction in ED length of stay for the group with EP-performed DVT studies vs the radiology department patients [ 102 ].

Ultrasound-guided peripheral venous catheter (PVC) insertion has been shown in some studies to reduce time and attempts [ 103 , 104 , 105 ], while others show similar or even worse success rate [ 106 , 107 , 108 ]. One study found that ultrasound-guided PVC insertion was associated with a higher rate of extravasation, 3.6% vs 0.3% [ 109 ]. Another study showed a 73% success of cannulation of the brachial or the basilic vein after two failed attempts without ultrasound, but also showed an 8% rate of extravasation at 1 h [ 110 ]. One group evaluated EPs use of PoCUS before peripheral venous cannulation of children less than 7 years before cannulation as usual, and found visible veins on ultrasound a strong predictor for successful cannulation [ 111 ]. It has also been found that EPs could insert a standard 2.5-in., 18-gauge peripheral venous catheter in the internal jugular vein with a success rate of 97.1% after two failed attempts by management as usual by nursing staff [ 112 ].

The main findings on diagnostic test accuracy of abdominal PoCUS are listed in Table  5 .

One meta-analysis of EPs’ findings of hydronephrosis as a surrogate for nephrolithiasis in patients presenting with renal colic found only moderate sensitivity and specificity [ 113 ]. Moderate-to-severe hydronephrosis is highly specific for the presence of a stone at 94%, but only with a sensitivity of 29%. One study not included in this meta-analysis found 100% sensitivity, but moderate specificity [ 114 ]. A French study found that EPs correctly identified hydronephrosis in children with urinary tract infections (prevalence = 5%) with a sensitivity of 76.5% and a specificity of 97.2% [ 115 ]. Finally, one large ( n  = 2759) study, randomising patients into diagnosis through EP PoCUS, radiologist ultrasound or computed tomography (CT), found no difference in high-risk diagnoses that could be due to missed or delayed diagnosis after 30 days, and showed overall lower cumulative radiation exposure at 6 months for both ultrasound groups compared to the CT group [ 116 ]. They also showed a slight, but significant, reduction in ED length of stay, while another study found halving of the length of stay [ 117 ].

Only one small, retrospective study reviewed EPs diagnostic accuracy of scrotal PoCUS, and found that the EPs correctly diagnosed epididymitis, orchitis, and testicular torsion in 35 of 36 cases [ 118 ]. No cases of testicular torsion were missed.

Two Norwegian studies demonstrated clinical usefulness for the use of GP operated PoCUS to demonstrate cholelithiasis already in the 80s [ 119 , 120 ], and also a more recent study shows high agreement between GP and radiologist performed ultrasound [ 121 ]. In the ED setting, a high accuracy was shown already in a 1994 study [ 122 ] and Blaivas et al. [ 123 ] showed a significant reduction in the length of stay in the emergency department when EPs used PoCUS for diagnosis of biliary disease. One meta-analysis found an LR+ of 7.5 and LR− of 0.12 on EP-performed PoCUS for cholelithiasis [ 124 ], similar to a large, retrospective study not included in the meta-analysis [ 125 ]. A similar high specificity was found in a more recent study, and a sensitivity of 55% when using eventual need for cholecystectomy as their gold standard [ 126 ]. When it comes to cholecystitis, the LR+ ranged from 4.2 to 4.7 and the LR− from 0.05 to 0.39 in three studies of varying design [ 127 , 128 , 129 ]. Summers et al. [ 128 ] found that there were close agreement with radiology department ultrasound when compared to the criterion standard of surgical reports and follow-up, and suggested that patients with negative EP scans are unlikely to require surgery. Another study could not conclude the same, as they, in contrast to the other studies, only found 38% sensitivity using surgical findings as the criterion standard [ 130 ]. The positive likelihood ratio was high nevertheless, as specificity in their study was 100%. A Turkish study found that diagnosis and management were more likely to be affected if the clinician had moderate, rather than low or high, suspicion about the diagnosis prior to the study [ 131 ]. One study performed PoCUS on patients presenting with non-traumatic epigastric pain, and found a cholelithiasis prevalence of 39% in this population, even though the treating EP did not initially consider the need for biliary ultrasound in 85% of these cases [ 132 ]. A USA study found that the presence of a dilated common bile duct on EP-performed PoCUS, in the absence of laboratory findings or signs of cholecystitis on ultrasound, was unlikely to be a good indicator for complicated biliary pathology (sensitivity 23.7% and specificity 77.9%) [ 133 ].

Appendicitis has several hall-mark findings such as oedematous wall and overall thickness. One meta-analysis found an LR+ of 9.24 on EP-performed ultrasound for appendicitis in children [ 134 ], reproduced in one study published since [ 135 ]. Lee and Yun [ 136 ] found LR+ of 7.0 in a 2019 meta-analysis of PoCUS on all ages, while Fields et al. [ 137 ] found LR+ of 10.2 in their sub-group analysis of EP-performed PoCUS for appendicitis in a 2017 meta-analysis. The LR−, however, ranged from 0.17 to 0.22, and one can conclude that EP-performed PoCUS is useful to rule in appendicitis, but not sufficient on its own to rule it out. This can also be concluded from the latest three studies not included in the above-mentioned meta-analyses [ 138 , 139 , 140 ].

Concentric rings on ultrasound of the small bowel indicate intussusception in children in whom one suspects this condition [ 141 ]. We identified one prospective observational study and one retrospective analysis of EP-performed PoCUS for intussusception after only short periods of training, both showing high specificities of 94–97%, but varying sensitivities of 85–100% [ 141 , 142 ]. One retrospective study was limited by its design giving an absence of true negative findings, but showed sensitivity of 79% in novices and 90% in a certified paediatric EP [ 143 ], while a South Korean group found that PoCUS significantly reduced the door-to-reduction time and overall stay in their ED [ 144 ].

Small bowel obstruction can be seen using ultrasound by identifying features such as small bowel dilation, abnormal peristalsis, small bowel wall oedema, and intraperitoneal free fluid [ 145 ]. Four studies in the ED showed sensitivities from 88 to 98% [ 145 , 146 , 147 , 148 ], with two studies showing a higher sensitivity, but lower specificity for EPs than for radiologist ultrasound when compared to CT [ 146 , 147 ]. One of the studies showed lower specificity than the other three studies (54% vs 84–94%), citing a shorter didactic session and experience requirements as a possible explanation [ 145 ].

One small study found that GPs had 100% agreement with radiologists on the use of PoCUS for finding ascites on indication [ 93 ].

A small study ( n  = 50) compared ultrasound measured transverse diameter of the rectum against Roma III criteria for constipation in children, and found high sensitivity of 86%, but a somewhat low specificity of 71% [ 149 ]. However, ultrasound was not less sensitive than abdominal X-ray (87%) and trended towards being more specific (71% vs 40%). A rectal diameter of 3.8 cm or greater correlated well with constipation.

Two studies were identified using several of the above-mentioned techniques to help diagnose patients presenting with abdominal pain and found an overall improvement in diagnostic accuracy compared to work-up as usual [ 150 , 151 ].

Obstetric ultrasound

Inexperienced Danish GPs had 28 of 30 measurements of gestational age (GA) within 3 days of the obstetrician performed estimate, while the final 2 were within 7 days [ 93 ]. Johansen et al. [ 152 ] found that GP’s measurements of GA in an 11 year period ( n  = 356) showed the same agreement with actual date of birth as did those of the local obstetric service ( n  = 14,550). The same agreement was found in six other GP studies between 1985 and 2001 [ 153 , 154 , 155 , 156 , 157 , 158 ].

Also EP measured crown-rump length (CRL), used in first trimester estimation of GA, showed in two studies correlation coefficients of 0.95–0.98 when compared with obstetric ultrasound [ 159 , 160 ]. Another study found that EPs were accurate stratifying GA into before and after 24 weeks, and thus foetal potential viability if one decides to go ahead with an emergent caesarean section in patients unable to give an accurate history due to lowered consciousness [ 161 ].

One meta-analysis assessed EPs’ accuracy in diagnosing ectopic pregnancy by PoCUS, defining a positive finding as an empty uterus in a patient with a confirmed pregnancy [ 162 ]. Using this “safe” definition, the pooled sensitivity was high at 99.3%, while the specificity ranged from 42 to 89%, pooled specificity estimate not being possible to calculate due to study heterogeneity.

Another meta-analysis included six studies aimed to show whether EP-performed pelvic ultrasound on women with symptomatic early pregnancy in the ED caused a reduction in the length of stay (LOS) in the ED, and confirmed this, with a mean reduction in LOS of 74 min (95% CI 49–99) [ 163 ].

Among those visiting ED due to bleeding in the first trimester, one study showed 42% had the expectation of getting confirmation of foetal viability by ultrasound and blood work [ 164 ]. In addition to identifying an intrauterine pregnancy, confirming foetal heart activity is decisive in diagnosing a threatened or missed abortion. We identified four studies where GPs had 100% accuracy (total n  = 295) [ 93 , 152 , 153 , 165 ] and one study of EPs showing a sensitivity of 89% and a specificity of 100% by use of transabdominal transducer [ 166 ]. In this study, mean GA was 9.5 weeks, and only the heart activity of the very earliest pregnancies was missed when compared to a radiologist using transvaginal transducer.

Two studies (total n  = 387) showed that both GPs and EPs had 100% accuracy in detecting foetal position in the third trimester [ 152 , 167 ].

Studies on ocular PoCUS are listed in Table  6 . Retinal detachment may be seen on ultrasound as a hyperechoic line separating from the choroid while being tethered to the optic disc. One recent meta-analysis determined the test characteristics of ocular PoCUS for this condition [ 168 ]. A sub-group analysis of five studies where the provider was an EP working in the ED found a sensitivity of 94% and a specificity of 91%. One retrospective study excluded from this meta-analysis, due to its retrospective design, showed similar numbers [ 169 ], as did two more recent prospective studies [ 170 , 171 ] (see Table  6 ).

One study was identified estimated test accuracies for the important differential diagnoses of vitreous haemorrhage and detachment, and found high total accuracy for haemorrhage and high specificity for vitreous detachment [ 170 ]. Another study evaluated 232 patients (351 eyes) after trauma (excluding obvious globe rupture), and found high accuracy for the detection of vitreous haemorrhage, lens dislocation, globe foreign body, globe rupture, and retrobulbar haematoma [ 171 ]. The same group also found high accuracy for the detection of traumatic lens dislocation in a different study 5 years previously [ 172 ].

Soft tissue

Linear, high-frequency ultrasound can give detailed images of structures in the soft tissue, and findings from studies are summarized in Table  7 . A 2017 meta-analysis included eight studies on adult and paediatric ED populations determining the accuracy of EPs using PoCUS to detect the presence of an abscess in patients presenting with signs of skin and soft-tissue infection, and found a pooled sensitivity of 96% and a specificity of 83% [ 173 ]. The pooled sensitivity of the paediatric sub-group was slightly lower at 94%, but had the same specificity. The decision of whether to lance or not was changed in 14–56% of the cases. Pre-study teaching varied from 15 min to 1 day. A 2016 meta-analysis including six studies showed the same test accuracy [ 174 ]. Another study compared EP PoCUS and CT for abscesses head-to-head and found significantly better sensitivity for PoCUS (97% vs 77%), and similar specificity (86% vs 91% with overlapping 95% confidence intervals) [ 175 ]. In a primary care outpatient setting, it has been showed that the size of abscesses was estimated incorrectly by clinical examination in 52% of cases and ultrasound changed management in 55% of cases [ 176 ]. One study compared the test accuracy of clinical examination with and without PoCUS on finding soft-tissue abscesses [ 177 ]. They found very high accuracy and no significant difference between the groups in the population for which the EP indicated that she was clinically certain about the diagnosis ( n  = 1111). However, in the uncertain cases ( n  = 105), ultrasound changed management in a quarter, appropriately so in 85% of these. Also in a paediatric ED population, it was found that ultrasound did not change the ED treatment failure rate, even though ultrasound changed management from surgical to medical or vice versa in 25% of cases [ 178 ]. This is in contrary to another study in a paediatric population who did see a significant reduction in failure rate, with three times higher failure rates in the non-PoCUS vs PoCUS groups (14% vs 4%) [ 179 ]. The same group found similar rates in adults ( n  = 125), with 17% vs 3.7%, but the 95% confidence intervals showed 0–19.4% difference between the groups, leaving it barely statistically significant [ 180 ]. A US study showed that the ED length of stay was significantly reduced, by a mean of 73 min, when patients received EP PoCUS rather than radiology ultrasound [ 181 ]. They also found significant differences in the two groups on incision and drainage rate which was twice as high in the PoCUS group and rate of ED intravenous antibiotics, which was 60%.

Two small studies on the use of PoCUS for the detection of peritonsillar abscess [ 182 ] and dental abscess [ 183 ] showed near 100% test accuracy, but had wide confidence intervals due to small populations.

Two studies ( n  = 27 and n  = 75) evaluated EP PoCUS diagnostic accuracy on paediatric soft-tissue neck masses and found a Cohen’s kappa coefficient when compared to the final diagnosis of 0.69 (95% CI 0.44–0.94) and 0.71 (0.60–0.83), respectively [ 184 , 185 ].

One clinical study on the use of PoCUS for identification of soft-tissue foreign bodies showed that ultrasound identified two-thirds of all foreign bodies with a specificity of 97% [ 186 ]. There were no significant differences in performance characteristics of X-ray which showed sensitivity of 58% and a specificity of 90%.

Musculoskeletal ultrasound

The retrieved studies on musculoskeletal ultrasound were on the ability to detect acute tendon trauma, joint fluid, shoulder dislocation, and bone fractures, and the test accuracy findings are summarized in Table  8 .

Two studies studied the accuracy of EP-performed PoCUS on suspected ligamentous injuries in the ulnar part of the wrist and showed high specificity, but mixed sensitivity [ 187 , 188 ], using magnetic resonance imaging (MRI) as the criterion standard. Two studies evaluating the same in the ankle showed high test accuracies against the same Ref. [ 189 , 190 ]. A US study showed a higher specificity for ligamentous laceration on extremity penetrating trauma than clinical examination without ultrasound when compared to surgical exploration or MRI [ 191 ], and this study and an Iranian study [ 192 ] showed 94–100% sensitivity and specificity.

Two studies showed high specificity (both 98%) for paediatric hip effusions, but a somewhat reduced sensitivity of 80–85%, compared to a chart review or radiologist performed ultrasound [ 193 , 194 ]. One study showed that 50% of planned joint aspirations were avoided after PoCUS of swollen joints [ 195 ].

One meta-analysis on the use of PoCUS on patients with shoulder dislocations included seven studies ( n  = 739), and showed 99.1% sensitivity and 99.8% specificity when compared to X-ray [ 196 ]. The accuracy was similar for associated fractures, but one could not determine the clinical significance due to wide confidence intervals.

A South Korean study found high accuracy for the detection of anterior and posterior cruciate ligament tears by PoCUS [ 197 ].

Finding or excluding a bony fracture could be a useful utility of ultrasound in a GP setting given a high enough accuracy, as X-ray is usually not immediately available and may require significant travelling for the patient. We identified three meta-analyses and 25 primary studies evaluating the test accuracy of EP-performed ultrasound on different fractures, all summarized in Table  8 . The main finding is that there is generally a very high sensitivity and specificity for detecting the cortical disruption representing the fracture ultrasound, but less for fractures near joints.

Six diagnostic accuracy studies on the use of EP-performed PoCUS to detect paediatric skull fractures found sensitivities ranging from 77 to 100 and specificities from 85 to 100 [ 198 , 199 , 200 , 201 , 202 , 203 ].

Clavicular fractures were studied in three studies, all showing high accuracy [ 198 , 204 , 205 ], with false-negative cases being clinically non-significant green-stick fractures.

One meta-analysis of ultrasound for elbow fractures included a sub-group analysis of five studies where the operators were EPs, and showed a specificity of 95% and a sensitivity of 94% [ 206 ]. Elbow fractures can be identified on ultrasound by cortical disruption and/or posterior fat pad sign. The latter is rare in radial head subluxation without fractures according to a US study, indicating that PoCUS may be an adequate rule out test before reduction of the subluxation [ 207 ].

One meta-analysis assessed the test characteristics of ultrasound to detect paediatric forearm fractures [ 208 ] and found sensitivity and specificity of 93, and also two studies published since showed high accuracy [ 209 , 210 ]. Another meta-analysis, also including studies with adults, showed even higher accuracy with a pooled sensitivity of 97% and a specificity of 95% [ 211 ], and also showed no significant accuracy differences between inexperienced and experienced physicians. A Turkish study published after this meta-analysis has shown similar test accuracy in adults [ 212 ].

Studies on metacarpal and phalangeal fractures showed sensitivities ranging from 79 to 100% and specificities from 87 to 98%, with the poorest accuracy for periarticular fractures and for the third and fourth metacarpal bones which are only available to scan from two surfaces [ 213 , 214 , 215 , 216 , 217 , 218 , 219 ]. The study of the distal phalanx fractures also assessed the accuracy of PoCUS to detect nail bed injuries before lifting the nail and visually inspecting, and found a 93% sensitivity and 100% specificity for this [ 218 ].

One study aimed to determine the combined accuracy for any tibia or fibula fracture, and found 100% sensitivity and 93% specificity against X-ray, and also found that all false positives were true positives when compared to CT, indicating a higher accuracy than X-ray [ 220 ].

One study showed poor sensitivity for navicular bone fracture [ 221 ].

One meta-analysis from 2017 [ 208 ] and two more recent studies [ 222 , 223 ] all showed high accuracy in detection of fractures in the ankle malleoli. Three studies determined the accuracy of PoCUS specifically for fifth metatarsal fracture, and found total accuracies in the 90s [ 221 , 224 , 225 ].

Strengths and limitations

This review is based on a search strategy that was designed to be comprehensive and sensitive enough to identify all relevant meta-analyses and primary research papers available, and included studies written in English, Spanish, Norwegian, and Swedish. In addition, reference lists of included studies were manually searched to identify further studies to include. However, the search only included searches through PubMed/MEDLINE, not EMBASE or similar proprietary databases. The main screening was only performed by one of the authors, which could be a source of bias.

One comprehensive systematic review only including clinical studies on the training and use of PoCUS by GPs already exists [ 12 ]. Given the scarcity of data, it was difficult to draw conclusions other than PoCUS has a potential of being a valuable tool for the general practitioner. A strength of our review is the wealth of data on GP relevant indications which we draw on from our EP colleagues. However, this may be one of the main weaknesses as well, as even though there is a considerable overlap in knowledge and skill bases, generalist approach, and even populations, there are also considerable differences. GPs tend to work more independently with less possibility of daily peer interaction, and have a broader scope of practice, not only including working with patients with conditions which require immediate action. In areas where patients can self-refer to emergency departments staffed by EPs, the pre-test probability of any given diagnosis will be different, with a skew towards more life-threatening conditions in EDs compared to those presenting to primary care run services. However, in other regions, where GPs may, indeed, be the first responder to any emergency, this may not be the case.

Nevertheless, much of a GP’s evidence-based practice, is, and will likely always be, based on work done in other fields. In fact, there are most likely relevant studies on the use of ultrasound done by, e.g., physiotherapist, sports medicine physicians, paediatricians, internal medicine specialist, surgeons, etc., which also could be relevant for GPs.

The studies identified were heterogenous and ranged from small pilot studies, through prospective and retrospective convenience sample observational studies, some randomised control trials and on to large, rigorous meta-analyses. In terms of operators, they include in some cases one expert GP or EP sonographer, while, in other cases, the operators were many, of different levels of experience, including novices, all only receiving short, specific didactic interventions. There were no attempts at formally assessing the quality of the primary studies by available quality assessment tools, but most of the meta-analyses will have had such assessment done by their respective authors.

Being a very heterogenous group of physicians, it is hard to establish an absolute list of possible indications for which any given GP may find PoCUS of clinical relevance. We think that we have created an overview where most GPs can find some areas of interest, but also acknowledge that others may criticise the exclusion of indications listed in Appendix 1 .

Conclusions

This systematic review shows that ultrasound, at the point of care, is increasingly being utilised by GPs and EPs across the world. It also shows that generalists can, given a certain level of pre-test probability, safely use ultrasound in a wide range of clinical settings to aid diagnosis. For many conditions, the sensitivity is high and can help the physician rule out a condition, while for others, the specificity is high, helping to rule in a diagnosis. For some conditions, the total test accuracy is high, and it may, in fact, be a valuable screening tool. For some conditions, such as identifying foreign bodies and in shoulder dislocations, PoCUS seems to have similar accuracy as X-ray, while for others, such as rib fractures, tibia and fibula fractures, pneumothorax, pneumonia, and in patients presenting with pleuritic pain of any cause, it seems to outperform conventional X-ray. PoCUS has also shown to decrease the length of time to diagnosis and discharge in some settings, decrease failure rates of treatment, and to aid in difficult intravenous access.

GPs are by no means a homogenous group of physicians, neither are EPs. It is likely that if many EPs can learn to safely use clinical ultrasound, so can many interested GPs, as both groups are trained and used to applying a wide range of methods to assess a wide range of patients and conditions. It is likely that the patient population will vary from GP to GP as well, as we all work in different regions with populations of different disease prevalence profiles and health service seeking behaviors. It is important for both GPs and EPs to be aware of one’s population’s characteristics and pre-test probabilities for any given condition with regards to all aspects of clinical work, including history taking, examination, and diagnostic studies. Given the varying prevalence in each clinician’s population, we, therefore, encourage the use of the likelihood ratios using Fagan’s nomogram [ 226 ], which as a pre-requisite for usage only requires an estimate of pre-test likelihood rather than having the exact same prevalence as in the respective studies from which the data were obtained.

This systematic review will potentially be a valuable reference for physicians searching for evidence for the use of PoCUS in their given primary care setting. Even though most of the studies involved ultrasound performed by EPs, we believe what has been found is relevant also in a GP setting, and is, to date, the best evidence available. We hope also that our review can be of value in showing the need for further research in a primary care setting, and we see a need for more rigorous study designs, with more studies with multi-centre, randomised and controlled designs.

Availability of data and materials

The data sets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Abbreviations

abdominal aortic aneurysm

acute decompensated heart failure

coronary artery disease

chronic obstructive pulmonary disease

crown-rump length

computed tomography

chest X-ray

deep vein thrombosis

emergency department

emergency physician

gestational age

general practitioner/family physician

length of stay

positive likelihood ratio

negative likelihood ratio

lung ultrasound

left-ventricular ejection fraction

left-ventricular hypertrophy

mitral annular plane systolic excursion

medical subject headings

magnetic resonance imaging

out-of-hours

point-of-care ultrasound

pro-brain natriuretic peptide

peripheral venous catheter

Moore CL, Copel JA (2011) Point-of-care ultrasonography. N Engl J Med 364(8):749–757

Article   CAS   PubMed   Google Scholar  

Weile J, Brix J, Moellekaer AB (2018) Is point-of-care ultrasound disruptive innovation? Formulating why POCUS is different from conventional comprehensive ultrasound. Crit Ultrasound J 10(1):25

Article   PubMed   PubMed Central   Google Scholar  

Huibers L, Giesen P, Wensing M, Grol R (2009) Out-of-hours care in western countries: assessment of different organizational models. BMC Health Serv Res 9:105

Pandit T, Ray R, Sabesan S (2019) Review article: Managing medical emergencies in rural Australia: a systematic review of the training needs. Emerg Med Australas 31(1):20–28

Article   PubMed   Google Scholar  

Bosco C, Oandasan I (2016) Review of family medicine within rural and remote Canada: education, practice, and policy. The College of Family Physicians of Canada, Mississauga

Google Scholar  

Nieber T, Hansen EH, Bondevik GT (2007) Organization of Norwegian out-of-hours primary health care services. Tidsskr Nor Laegeforen 127:1335–1338

PubMed   Google Scholar  

St John and the PRIME programme. https://www.stjohn.org.nz/What-we-do/Community-programmes/Partnered-programmes/PRIME/ . Accessed 9 Sept 2019

Lopez DG, Hamdorf JM, Ward AM, Emery J (2006) Early trauma management skills in Australian general practitioners. ANZ J Surg 76(10):894–897

Huibers LAMJ, Moth G, Bondevik GT, Kersnik J, Huber CA, Christensen MB, Leutgeb R, Casado AM, Remmen R, Wensing M (2011) Diagnostic scope in out-of-hours primary care services in eight European countries: an observational study. BMC Fam Pract 12:30

Hall JWW, Holman H, Bornemann P, Barreto T, Henderson D, Bennett K, Chamberlain J, Maurer DM (2015) Point of care ultrasound in family medicine residency programs: a CERA study. Fam Med 47(9):706–711

Bornemann P, Barreto T (2018) Point-of-care ultrasonography in family medicine. Am Fam Physician 98(4):200–202

Andersen CA, Holden S, Vela J, Rathleff MS, Jensen MB (2019) Point-of-care ultrasound in general practice: a systematic review. Ann Fam Med 17(1):61–69

Myhr K, Sandvik H, Morken T, Hunskaar S (2017) Point-of-care ultrasonography in Norwegian out-of-hours primary health care. Scand J Prim Health Care 35(2):120–125

Mengel-Jørgensen T, Jensen MB (2016) Variation in the use of point-of-care ultrasound in general practice in various European countries. Results of a survey among experts. Eur J Gen Pract 22(4):274–277

Flynn CJ, Weppler A, Theodoro D, Haney E, Milne WK (2012) Emergency medicine ultrasonography in rural communities. Can J Rural Med 17(3):99–104

Léger P, Fleet R, Maltais-Giguère J, Plant J, Piette É, Légaré F, Poitras J (2015) A majority of rural emergency departments in the province of Quebec use point-of-care ultrasound: a cross-sectional survey. BMC Emerg Med 15:36

Article   PubMed   PubMed Central   CAS   Google Scholar  

Leschyna M, Hatam E, Britton S, Myslik F, Thompson D, Sedran R, VanAarsen K, Detombe S (2019) Current state of point-of-care ultrasound usage in Canadian emergency departments. Cureus 11(3):e4246

PubMed   PubMed Central   Google Scholar  

Bobbia X, Zieleskiewicz L, Pradeilles C, Hudson C, Muller L, Claret PG, Leone M, de La Coussaye J-E, Winfocus France Group (2017) The clinical impact and prevalence of emergency point-of-care ultrasound: a prospective multicenter study. Anaesth Crit Care Pain Med 36(6):383–389

Bobbia X, Abou-Badra M, Hansel N, Pes P, Petrovic T, Claret PG, Lefrant JY, de La Coussaye JE, Winfocus France Group (2017) Changes in the availability of bedside ultrasound practice in emergency rooms and prehospital settings in France. Anaesth Crit Care Pain Med 37(3):201–205

Nielsen K, Lauridsen JRM, Laursen CB, Brabrand M (2015) Physicians using ultrasound in Danish emergency departments are mostly summoned specialists. Scand J Trauma Resusc Emerg Med 23:51

Shi D, Walline JH, Yu X, Xu J, Song PP, Zhu H (2018) Evaluating and assessing the prevalence of bedside ultrasound in emergency departments in China. J Thorac Dis 10(5):2685–2690

Ahn C, Kim C, Kang BS, Choi HJ, Cho JH (2015) Variation of availability and frequency of emergency physician-performed ultrasonography between adult and pediatric patients in the academic emergency department in Korea. Clin Exp Emerg Med 2(1):16–23

Henwood PC, Beversluis D, Genthon AA et al (2014) Characterizing the limited use of point-of-care ultrasound in Colombian emergency medicine residencies. Int J Emerg Med 7(1):7

American College of Emergency Physicians (2017) Ultrasound guidelines: emergency, point-of-care and clinical ultrasound guidelines in medicine. Ann Emerg Med 69(5):e27–e54

Article   Google Scholar  

Moore CL, Molina AA, Lin H (2006) Ultrasonography in community emergency departments in the United States: access to ultrasonography performed by consultants and status of emergency physician-performed ultrasonography. Ann Emerg Med 47(2):147–153

Talley BE, Ginde AA, Raja AS, Sullivan AF, Espinola JA, Camargo CA Jr (2011) Variable access to immediate bedside ultrasound in the emergency department. West J Emerg Med 12(1):96–99

Herbst MK, Camargo CA Jr, Perez A, Moore CL (2015) Use of point-of-care ultrasound in Connecticut emergency departments. J Emerg Med 48(2):191–196.e2

Sanders JL, Noble VE, Raja AS, Sullivan AF, Camargo CA Jr (2015) Access to and use of point-of-care ultrasound in the emergency department. West J Emerg Med 16(5):747–752

Amini R, Wyman MT, Hernandez NC, Guisto JA, Adhikari S (2017) Use of emergency ultrasound in Arizona community emergency departments. J Ultrasound Med 36(5):913–921

Mengarelli M, Nepusz A, Kondrashova T (2018) A comparison of point-of-care ultrasonography use in rural versus urban emergency departments throughout Missouri. Mo Med 115(1):56–60

Bratland SZ (1985) Ultrasonic diagnosis in general practice. An evaluation study. Tidsskr Nor Laegeforen 105(28):1939–1940

CAS   PubMed   Google Scholar  

Gillespie ND, Pringle S (1998) A pilot study of the role of echocardiography in primary care. Br J Gen Pract 48(429):1182

CAS   PubMed   PubMed Central   Google Scholar  

Mjølstad OC, Snare SR, Folkvord L, Helland F, Grimsmo A, Torp H, Haraldseth O, Haugen BO (2012) Assessment of left ventricular function by GPs using pocket-sized ultrasound. Fam Pract 29(5):534–540

Evangelista L, Juncadella E, Copetti S, Pareja A, Torrabadella J, Evangelista A (2013) Diagnostic usefulness of pocket echography performed in hypertensive patients by a general practitioner. Med Clin 141(1):1–7

Evangelista A, Galuppo V, Méndez J et al (2016) Hand-held cardiac ultrasound screening performed by family doctors with remote expert support interpretation. Heart 102(5):376–382

Moore CL, Rose GA, Tayal VS, Sullivan DM, Arrowood JA, Kline JA (2002) Determination of left ventricular function by emergency physician echocardiography of hypotensive patients. Acad Emerg Med 9(3):186–193

Randazzo MR, Snoey ER, Levitt MA, Binder K (2003) Accuracy of emergency physician assessment of left ventricular ejection fraction and central venous pressure using echocardiography. Acad Emerg Med 10(9):973–977

Secko MA, Lazar JM, Salciccioli LA, Stone MB (2011) Can junior emergency physicians use E-point septal separation to accurately estimate left ventricular function in acutely dyspneic patients? Acad Emerg Med 18(11):1223–1226

Bustam A, Noor Azhar M, Singh Veriah R, Arumugam K, Loch A (2014) Performance of emergency physicians in point-of-care echocardiography following limited training. Emerg Med J 31(5):369–373

McKaigney CJ, Krantz MJ, La Rocque CL, Hurst ND, Buchanan MS, Kendall JL (2014) E-point septal separation: a bedside tool for emergency physician assessment of left ventricular ejection fraction. Am J Emerg Med 32(6):493–497

Unlüer EE, Karagöz A, Akoğlu H, Bayata S (2014) Visual estimation of bedside echocardiographic ejection fraction by emergency physicians. West J Emerg Med 15(2):221–226

Shah SP, Shah SP, Fils-Aime R, Desir W, Joasil J, Venesy DM, Muruganandan KM (2016) Focused cardiopulmonary ultrasound for assessment of dyspnea in a resource-limited setting. Crit Ultrasound J 8(1):7

Farsi D, Hajsadeghi S, Hajighanbari MJ, Mofidi M, Hafezimoghadam P, Rezai M, Mahshidfar B, Abiri S, Abbasi S (2017) Focused cardiac ultrasound (FOCUS) by emergency medicine residents in patients with suspected cardiovascular diseases. J Ultrasound 20(2):133–138

Dehbozorgi A, Eslami Nejad S, Mousavi-Roknabadi RS, Sharifi M, Tafakori A, Jalli R (2019) Lung and cardiac ultrasound (LuCUS) protocol in diagnosing acute heart failure in patients with acute dyspnea. Am J Emerg Med. https://doi.org/10.1016/j.ajem.2019.02.040

Dinh VA, Ko HS, Rao R, Bansal RC, Smith DD, Kim TE, Nguyen HB (2012) Measuring cardiac index with a focused cardiac ultrasound examination in the ED. Am J Emerg Med 30(9):1845–1851

Betcher J, Majkrzak A, Cranford J, Kessler R, Theyyunni N, Huang R (2018) Feasibility study of advanced focused cardiac measurements within the emergency department. Crit Ultrasound J 10(1):10

Unlüer EE, Bayata S, Postaci N, Yeşil M, Yavaşi Ö, Kara PH, Vandenberk N, Akay S (2012) Limited bedside echocardiography by emergency physicians for diagnosis of diastolic heart failure. Emerg Med J 29(4):280–283

Ehrman RR, Russell FM, Ansari AH, Margeta B, Clary JM, Christian E, Cosby KS, Bailitz J (2015) Can emergency physicians diagnose and correctly classify diastolic dysfunction using bedside echocardiography? Am J Emerg Med 33(9):1178–1183

Del Rios M, Colla J, Kotini-Shah P, Briller J, Gerber B, Prendergast H (2018) Emergency physician use of tissue Doppler bedside echocardiography in detecting diastolic dysfunction: an exploratory study. Crit Ultrasound J 10(1):4

Nazerian P, Vanni S, Zanobetti M, Polidori G, Pepe G, Federico R, Cangioli E, Grifoni S (2010) Diagnostic accuracy of emergency Doppler echocardiography for identification of acute left ventricular heart failure in patients with acute dyspnea: comparison with Boston criteria and N-terminal prohormone brain natriuretic peptide. Acad Emerg Med 17(1):18–26

Saul T, Avitabile NC, Berkowitz R, Siadecki SD, Rose G, Toomarian M, Kaban NL, Governatori N, Suprun M (2016) The inter-rater reliability of echocardiographic diastolic function evaluation among emergency physician sonographers. J Emerg Med 51(4):411–417

Croft PE, Strout TD, Kring RM, Director L, Vasaiwala SC, Mackenzie DC (2019) WAMAMI: emergency physicians can accurately identify wall motion abnormalities in acute myocardial infarction. Am J Emerg Med. https://doi.org/10.1016/j.ajem.2019.03.037

Reardon L, Scheels WJ, Singer AJ, Reardon RF (2018) Feasibility and accuracy of speckle tracking echocardiography in emergency department patients. Am J Emerg Med 36(12):2254–2259

Mandavia DP, Hoffner RJ, Mahaney K, Henderson SO (2001) Bedside echocardiography by emergency physicians. Ann Emerg Med 38(4):377–382

Martindale JL, Wakai A, Collins SP, Levy PD, Diercks D, Hiestand BC, Fermann GJ, deSouza I, Sinert R (2016) Diagnosing acute heart failure in the emergency department: a systematic review and meta-analysis. Acad Emerg Med 23(3):223–242

McGivery K, Atkinson P, Lewis D, Taylor L, Harris T, Gadd K, Fraser J, Stoica G (2018) Emergency department ultrasound for the detection of B-lines in the early diagnosis of acute decompensated heart failure: a systematic review and meta-analysis. CJEM 20(3):343–352

Lian R, Zhang GC, Yan ST, Sun LC, Zhang SQ, Zhang GQ (2018) Role of ultrasound lung comets in the diagnosis of acute heart failure in emergency department: a systematic review and meta-analysis. Biomed Environ Sci 31(8):596–607

Maw AM, Hassanin A, Ho PM et al (2019) Diagnostic accuracy of point-of-care lung ultrasonography and chest radiography in adults with symptoms suggestive of acute decompensated heart failure: a systematic review and meta-analysis. JAMA Netw Open 2(3):e190703

Staub LJ, Mazzali Biscaro RR, Kaszubowski E, Maurici R (2019) Lung ultrasound for the emergency diagnosis of pneumonia, acute heart failure, and exacerbations of chronic obstructive pulmonary disease/asthma in adults: a systematic review and meta-analysis. J Emerg Med 56(1):53–69

Pivetta E, Goffi A, Nazerian P et al (2019) Lung ultrasound integrated with clinical assessment for the diagnosis of acute decompensated heart failure in the emergency department: a randomized controlled trial. Eur J Heart Fail. https://doi.org/10.1002/ejhf.1379

Baker K, Mitchell G, Stieler G (2013) Limited lung ultrasound protocol in elderly patients with breathlessness; agreement between bedside interpretation and stored images as acquired by experienced and inexperienced sonologists. Australas J Ultrasound Med 16(2):86–92

Orso D, Guglielmo N, Copetti R (2018) Lung ultrasound in diagnosing pneumonia in the emergency department: a systematic review and meta-analysis. Eur J Emerg Med 25(5):312–321

Ye X, Xiao H, Chen B, Zhang S (2015) Accuracy of lung ultrasonography versus chest radiography for the diagnosis of adult community-acquired pneumonia: review of the literature and meta-analysis. PLoS ONE 10(6):e0130066

Amatya Y, Rupp J, Russell FM, Saunders J, Bales B, House DR (2018) Diagnostic use of lung ultrasound compared to chest radiograph for suspected pneumonia in a resource-limited setting. Int J Emerg Med 11(1):8

Copetti R, Cattarossi L (2008) Ultrasound diagnosis of pneumonia in children. Radiol Med 113(2):190–198

Shah VP, Tunik MG, Tsung JW (2013) Prospective evaluation of point-of-care ultrasonography for the diagnosis of pneumonia in children and young adults. JAMA Pediatr 167(2):119–125

Yilmaz HL, Özkaya AK, Sarı Gökay S, Tolu Kendir Ö, Şenol H (2017) Point-of-care lung ultrasound in children with community acquired pneumonia. Am J Emerg Med 35(7):964–969

Jones BP, Tay ET, Elikashvili I, Sanders JE, Paul AZ, Nelson BP, Spina LA, Tsung JW (2016) Feasibility and safety of substituting lung ultrasonography for chest radiography when diagnosing pneumonia in children: a randomized controlled trial. Chest 150(1):131–138

Harel-Sterling M, Diallo M, Santhirakumaran S, Maxim T, Tessaro M (2019) Emergency department resource use in pediatric pneumonia: point-of-care lung ultrasonography versus chest radiography. J Ultrasound Med 38(2):407–414

Ebrahimi A, Yousefifard M, Mohammad Kazemi H, Rasouli HR, Asady H, Moghadas Jafari A, Hosseini M (2014) Diagnostic accuracy of chest ultrasonography versus chest radiography for identification of pneumothorax: a systematic review and meta-analysis. Tanaffos 13(4):29–40

Staub LJ, Biscaro RRM, Kaszubowski E, Maurici R (2018) Chest ultrasonography for the emergency diagnosis of traumatic pneumothorax and haemothorax: a systematic review and meta-analysis. Injury 49(3):457–466

Riccardi A, Spinola MB, Ghiglione V, Licenziato M, Lerza R (2019) PoCUS evaluating blunt thoracic trauma: a retrospective analysis of 18 months of emergency department activity. Eur J Orthop Surg Traumatol 29(1):31–35

Lalande É, Guimont C, Émond M, Parent MC, Topping C, Kuimi BLB, Boucher V, Le Sage N (2017) Feasibility of emergency department point-of-care ultrasound for rib fracture diagnosis in minor thoracic injury. CJEM 19(3):213–219

Pishbin E, Ahmadi K, Foogardi M, Salehi M, Seilanian Toosi F, Rahimi-Movaghar V (2017) Comparison of ultrasonography and radiography in diagnosis of rib fractures. Chin J Traumatol 20(4):226–228

Koh Y, Chua MT, Ho WH, Lee C, Chan GWH, Sen Kuan W (2018) Assessment of dyspneic patients in the emergency department using point-of-care lung and cardiac ultrasonography—a prospective observational study. J Thorac Dis 10(11):6221–6229

Bekgoz B, Kilicaslan I, Bildik F, Keles A, Demircan A, Hakoglu O, Coskun G, Demir HA (2019) BLUE protocol ultrasonography in emergency department patients presenting with acute dyspnea. Am J Emerg Med. https://doi.org/10.1016/j.ajem.2019.02.028

Volpicelli G, Cardinale L, Berchialla P, Mussa A, Bar F, Frascisco MF (2012) A comparison of different diagnostic tests in the bedside evaluation of pleuritic pain in the ED. Am J Emerg Med 30(2):317–324

Goffi A, Pivetta E, Lupia E, Porrino G, Civita M, Laurita E, Griot G, Casoli G, Cibinel G (2013) Has lung ultrasound an impact on the management of patients with acute dyspnea in the emergency department? Crit Care 17(4):R180

Laursen CB, Sloth E, Lambrechtsen J, Lassen AT, Madsen PH, Henriksen DP, Davidsen JR, Rasmussen F (2013) Focused sonography of the heart, lungs, and deep veins identifies missed life-threatening conditions in admitted patients with acute respiratory symptoms. Chest 144(6):1868–1875

Laursen CB, Sloth E, Lassen AT, Christensen RD, Lambrechtsen J, Madsen PH, Henriksen DP, Davidsen JR, Rasmussen F (2014) Point-of-care ultrasonography in patients admitted with respiratory symptoms: a single-blind, randomised controlled trial. Lancet Respir Med 2(8):638–646

Zanobetti M, Scorpiniti M, Gigli C et al (2017) Point-of-care ultrasonography for evaluation of acute dyspnea in the ED. Chest 151(6):1295–1301

Seyedhosseini J, Bashizadeh-Fakhar G, Farzaneh S, Momeni M, Karimialavijeh E (2017) The impact of the BLUE protocol ultrasonography on the time taken to treat acute respiratory distress in the ED. Am J Emerg Med 35(12):1815–1818

Buhumaid RE, St-Cyr Bourque J, Shokoohi H, Ma IWY, Longacre M, Liteplo AS (2019) Integrating point-of-care ultrasound in the ED evaluation of patients presenting with chest pain and shortness of breath. Am J Emerg Med 37(2):298–303

Zanobetti M, Poggioni C, Pini R (2011) Can chest ultrasonography replace standard chest radiography for evaluation of acute dyspnea in the ED? Chest 139(5):1140–1147

Sforza A, Mancusi C, Carlino MV, Buonauro A, Barozzi M, Romano G, Serra S, de Simone G (2017) Diagnostic performance of multi-organ ultrasound with pocket-sized device in the management of acute dyspnea. Cardiovasc Ultrasound 15(1):16

Carlino MV, Paladino F, Sforza A, Serra C, Liccardi F, de Simone G, Mancusi C (2018) Assessment of left atrial size in addition to focused cardiopulmonary ultrasound improves diagnostic accuracy of acute heart failure in the emergency department. Echocardiography 35(6):785–791

Papanagnou D, Secko M, Gullett J, Stone M, Zehtabchi S (2017) Clinician-performed bedside ultrasound in improving diagnostic accuracy in patients presenting to the ED with acute dyspnea. West J Emerg Med 18(3):382–389

Blois B (2012) Office-based ultrasound screening for abdominal aortic aneurysm. Can Fam Physician 58(3):e172–e178

Bailey RP, Ault M, Greengold NL, Rosendahl T, Cossman D (2001) Ultrasonography performed by primary care residents for abdominal aortic aneurysm screening. J Gen Intern Med 16(12):845–849

Article   CAS   PubMed   PubMed Central   Google Scholar  

Bravo-Merino L, González-Lozano N, Maroto-Salmón R, Meijide-Santos G, Suárez-Gil P, Fañanás-Mastral A (2019) Validity of the abdominal ecography in primary care for detection of aorta abdominal aneurism in male between 65 and 75 years. Aten Primaria 51(1):11–17

Sisó-Almirall A, Kostov B, Navarro González M et al (2017) Abdominal aortic aneurysm screening program using hand-held ultrasound in primary healthcare. PLoS ONE 12(4):e0176877

Hoffmann B, Um P, Bessman ES, Ding R, Kelen GD, McCarthy ML (2009) Routine screening for asymptomatic abdominal aortic aneurysm in high-risk patients is not recommended in emergency departments that are frequently crowded. Acad Emerg Med 16(11):1242–1250

Lindgaard K, Riisgaard L (2017) Validation of ultrasound examinations performed by general practitioners. Scand J Prim Health Care 35(3):256–261

Rubano E, Mehta N, Caputo W, Paladino L, Sinert R (2013) Systematic review: emergency department bedside ultrasonography for diagnosing suspected abdominal aortic aneurysm. Acad Emerg Med 20(2):128–138

Okahara A, Sadamatsu K, Matsuura T, Koga Y, Mine D, Yoshida K (2016) Coronary artery disease screening with carotid ultrasound examination by a primary care physician. Cardiol Res Pract 7(1):9–16

Mumoli N, Vitale J, Giorgi-Pierfranceschi M et al (2017) General practitioner-performed compression ultrasonography for diagnosis of deep vein thrombosis of the leg: a multicenter, prospective cohort study. Ann Fam Med 15(6):535–539

Pomero F, Dentali F, Borretta V, Bonzini M, Melchio R, Douketis JD, Fenoglio LM (2013) Accuracy of emergency physician-performed ultrasonography in the diagnosis of deep-vein thrombosis: a systematic review and meta-analysis. Thromb Haemost 109(1):137–145

Lee JH, Lee SH, Yun SJ (2019) Comparison of 2-point and 3-point point-of-care ultrasound techniques for deep vein thrombosis at the emergency department: a meta-analysis. Medicine 98(22):e15791

Torres-Macho J, Antón-Santos JM, García-Gutierrez I et al (2012) Initial accuracy of bedside ultrasound performed by emergency physicians for multiple indications after a short training period. Am J Emerg Med 30(9):1943–1949

Crowhurst TD, Dunn RJ (2013) Sensitivity and specificity of three-point compression ultrasonography performed by emergency physicians for proximal lower extremity deep venous thrombosis. Emerg Med Australas 25(6):588–596

Nygren D, Hård Af Segerstad C, Ellehuus Hilmersson C, Elf J, Ulf E, Lundager Forberg J (2018) Good outcomes when emergency physicians diagnosed deep vein thrombosis. Lakartidningen 115(3):92–95

Seyedhosseini J, Fadavi A, Vahidi E, Saeedi M, Momeni M (2018) Impact of point-of-care ultrasound on disposition time of patients presenting with lower extremity deep vein thrombosis, done by emergency physicians. Turk J Emerg Med 18(1):20–24

Costantino TG, Parikh AK, Satz WA, Fojtik JP (2005) Ultrasonography-guided peripheral intravenous access versus traditional approaches in patients with difficult intravenous access. Ann Emerg Med 46(5):456–461

Dargin JM, Rebholz CM, Lowenstein RA, Mitchell PM, Feldman JA (2010) Ultrasonography-guided peripheral intravenous catheter survival in ED patients with difficult access. Am J Emerg Med 28(1):1–7

Vinograd AM, Zorc JJ, Dean AJ, Abbadessa MKF, Chen AE (2018) First-attempt success, longevity, and complication rates of ultrasound-guided peripheral intravenous catheters in children. Pediatr Emerg Care 34(6):376–380

Stein J, George B, River G, Hebig A, McDermott D (2009) Ultrasonographically guided peripheral intravenous cannulation in emergency department patients with difficult intravenous access: a randomized trial. Ann Emerg Med 54(1):33–40

Oakley E, Wong A-M (2010) Ultrasound-assisted peripheral vascular access in a paediatric ED. Emerg Med Australas 22(2):166–170

Otani T, Morikawa Y, Hayakawa I et al (2018) Ultrasound-guided peripheral intravenous access placement for children in the emergency department. Eur J Pediatr 177(10):1443–1449

Rupp JD, Ferre RM, Boyd JS, Dearing E, McNaughton CD, Liu D, Jarrell KL, McWade CM, Self WH (2016) Extravasation risk using ultrasound-guided peripheral intravenous catheters for computed tomography contrast administration. Acad Emerg Med 23(8):918–921

Keyes LE, Frazee BW, Snoey ER, Simon BC, Christy D (1999) Ultrasound-guided brachial and basilic vein cannulation in emergency department patients with difficult intravenous access. Ann Emerg Med 34(6):711–714

Schnadower D, Lin S, Perera P, Smerling A, Dayan P (2007) A pilot study of ultrasound analysis before pediatric peripheral vein cannulation attempt. Acad Emerg Med 14(5):483–485

Zitek T, Busby E, Hudson H, McCourt JD, Baydoun J, Slattery DE (2018) Ultrasound-guided placement of single-lumen peripheral intravenous catheters in the internal jugular vein. West J Emerg Med 19(5):808–812

Wong C, Teitge B, Ross M, Young P, Robertson HL, Lang E (2018) The accuracy and prognostic value of point-of-care ultrasound for nephrolithiasis in the emergency department: a systematic review and meta-analysis. Acad Emerg Med 25(6):684–698

Javaudin F, Mounier F, Pes P, Arnaudet I, Vignaud F, Frampas E, Le Conte P, Winfocus-France study group (2017) Evaluation of a short formation on the performance of point-of-care renal ultrasound performed by physicians without previous ultrasound skills: prospective observational study. Crit Ultrasound J 9(1):23

Guedj R, Escoda S, Blakime P, Patteau G, Brunelle F, Cheron G (2015) The accuracy of renal point of care ultrasound to detect hydronephrosis in children with a urinary tract infection. Eur J Emerg Med 22(2):135–138

Smith-Bindman R, Aubin C, Bailitz J et al (2014) Ultrasonography versus computed tomography for suspected nephrolithiasis. N Engl J Med 371(12):1100–1110

Park YH, Jung RB, Lee YG, Hong CK, Ahn J-H, Shin TY, Kim YS, Ha YR (2016) Does the use of bedside ultrasonography reduce emergency department length of stay for patients with renal colic?: a pilot study. Clin Exp Emerg Med 3(4):197–203

Blaivas M, Sierzenski P, Lambert M (2001) Emergency evaluation of patients presenting with acute scrotum using bedside ultrasonography. Acad Emerg Med 8(1):90–93

Bratland SZ, Nordshus T (1985) Ultrasonography of the gallbladder in general practice. Tidsskr Nor Laegeforen 105(28):1946–1948

Eggebø TM, Sørvang S, Dalaker K (1990) Ultrasonic diagnosis of the upper abdomen performed in general practice. Tidsskr Nor Laegeforen 110(9):1096–1098

Esquerrà M, Roura Poch P, Masat Ticó T, Canal V, Maideu Mir J, Cruxent R (2012) Abdominal ultrasound: a diagnostic tool within the reach of general practitioners. Aten Primaria 44(10):576–583

Schlager D, Lazzareschi G, Whitten D, Sanders AB (1994) A prospective study of ultrasonography in the ED by emergency physicians. Am J Emerg Med 12(2):185–189

Blaivas M, Harwood RA, Lambert MJ (1999) Decreasing length of stay with emergency ultrasound examination of the gallbladder. Acad Emerg Med 6(10):1020–1023

Ross M, Brown M, McLaughlin K, Atkinson P, Thompson J, Powelson S, Clark S, Lang E (2011) Emergency physician-performed ultrasound to diagnose cholelithiasis: a systematic review. Acad Emerg Med 18(3):227–235

Scruggs W, Fox JC, Potts B, Zlidenny A, McDonough J, Anderson CL, Larson J, Barajas G, Langdorf MI (2008) Accuracy of ED bedside ultrasound for identification of gallstones: retrospective analysis of 575 studies. West J Emerg Med 9(1):1–5

Hilsden R, Leeper R, Koichopolos J, Vandelinde JD, Parry N, Thompson D, Myslik F (2018) Point-of-care biliary ultrasound in the emergency department (BUSED): implications for surgical referral and emergency department wait times. Trauma Surg Acute Care Open 3(1):e000164

Rosen CL, Brown DF, Chang Y, Moore C, Averill NJ, Arkoff LJ, McCabe CJ, Wolfe RE (2001) Ultrasonography by emergency physicians in patients with suspected cholecystitis. Am J Emerg Med 19(1):32–36

Summers SM, Scruggs W, Menchine MD, Lahham S, Anderson C, Amr O, Lotfipour S, Cusick SS, Fox JC (2010) A prospective evaluation of emergency department bedside ultrasonography for the detection of acute cholecystitis. Ann Emerg Med 56(2):114–122

Shekarchi B, Hejripour Rafsanjani SZ, Shekar Riz Fomani N, Chahardoli M (2018) Emergency department bedside ultrasonography for diagnosis of acute cholecystitis; a diagnostic accuracy study. Emergency 6(1):e11

Tootian Tourghabe J, Arabikhan HR, Alamdaran A, Zamani Moghadam H (2018) Emergency medicine resident versus radiologist in detecting the ultrasonographic signs of acute cholecystitis; a diagnostic accuracy study. Emergency 6(1):e19

Bektas F, Eken C, Soyuncu S, Kusoglu L, Cete Y (2009) Contribution of goal-directed ultrasonography to clinical decision-making for emergency physicians. Emerg Med J 26(3):169–172

Adhikari S, Morrison D, Lyon M, Zeger W, Krueger A (2014) Utility of point-of-care biliary ultrasound in the evaluation of emergency patients with isolated acute non-traumatic epigastric pain. Intern Emerg Med 9(5):583–587

Lahham S, Becker BA, Gari A, Bunch S, Alvarado M, Anderson CL, Viquez E, Spann SC, Fox JC (2018) Utility of common bile duct measurement in ED point of care ultrasound: a prospective study. Am J Emerg Med 36(6):962–966

Benabbas R, Hanna M, Shah J, Sinert R (2017) Diagnostic accuracy of history, physical examination, laboratory tests, and point-of-care ultrasound for pediatric acute appendicitis in the emergency department: a systematic review and meta-analysis. Acad Emerg Med 24(5):523–551

Nicole M, Desjardins MP, Gravel J (2018) Bedside sonography performed by emergency physicians to detect appendicitis in children. Acad Emerg Med. https://doi.org/10.1111/acem.13445

Lee SH, Yun SJ (2019) Diagnostic performance of emergency physician-performed point-of-care ultrasonography for acute appendicitis: a meta-analysis. Am J Emerg Med 37(4):696–705

Fields JM, Davis J, Alsup C, Bates A, Au A, Adhikari S, Farrell I (2017) Accuracy of point-of-care ultrasonography for diagnosing acute appendicitis: a systematic review and meta-analysis. Acad Emerg Med 24(9):1124–1136

Shahbazipar M, Seyedhosseini J, Vahidi E, Sheikh Motahar Vahedi H, Jahanshir A (2018) Accuracy of ultrasound exam performed by emergency medicine versus radiology residents in the diagnosis of acute appendicitis. Eur J Emerg Med. https://doi.org/10.1097/MEJ.0000000000000547

Sharif S, Skitch S, Vlahaki D, Healey A (2018) Point-of-care ultrasound to diagnose appendicitis in a Canadian emergency department. CJEM 20(5):732–735

Corson-Knowles D, Russell FM (2018) Clinical ultrasound is safe and highly specific for acute appendicitis in moderate to high pre-test probability patients. West J Emerg Med 19(3):460–464

Riera A, Hsiao AL, Langhan ML, Goodman TR, Chen L (2012) Diagnosis of intussusception by physician novice sonographers in the emergency department. Ann Emerg Med 60(3):264–268

Lam SHF, Wise A, Yenter C (2014) Emergency bedside ultrasound for the diagnosis of pediatric intussusception: a retrospective review. World J Emerg Med 5(4):255–258

Chang Y-J, Hsia S-H, Chao H-C (2013) Emergency medicine physicians performed ultrasound for pediatric intussusceptions. Biomed J 36(4):175–178

Kim JH, Lee J-Y, Kwon JH, Cho H-R, Lee JS, Ryu J-M (2017) Point-of-care ultrasound could streamline the emergency department workflow of clinically nonspecific intussusception. Pediatr Emerg Care. https://doi.org/10.1097/PEC.0000000000001283

Becker BA, Lahham S, Gonzales MA, Nomura JT, Bui MK, Truong TA, Stahlman BA, Fox JC, Kehrl T (2019) A prospective, multicenter evaluation of point-of-care ultrasound for small-bowel obstruction in the emergency department. Acad Emerg Med. https://doi.org/10.1111/acem.13713

Unlüer EE, Yavaşi O, Eroğlu O, Yilmaz C, Akarca FK (2010) Ultrasonography by emergency medicine and radiology residents for the diagnosis of small bowel obstruction. Eur J Emerg Med 17(5):260–264

Jang TB, Schindler D, Kaji AH (2011) Bedside ultrasonography for the detection of small bowel obstruction in the emergency department. Emerg Med J 28(8):676–678

Frasure SE, Hildreth AF, Seethala R, Kimberly HH (2018) Accuracy of abdominal ultrasound for the diagnosis of small bowel obstruction in the emergency department. World J Emerg Med 9(4):267–271

Doniger SJ, Dessie A, Latronica C (2018) Measuring the transrectal diameter on point-of-care ultrasound to diagnose constipation in children. Pediatr Emerg Care 34(3):154–159

Hasani SA, Fathi M, Daadpey M, Zare MA, Tavakoli N, Abbasi S (2015) Accuracy of bedside emergency physician performed ultrasound in diagnosing different causes of acute abdominal pain: a prospective study. Clin Imaging 39(3):476–479

Bourcier J-E, Gallard E, Redonnet J-P, Majourau M, Deshaie D, Bourgeois J-M, Garnier D, Geeraerts T (2018) Diagnostic performance of abdominal point of care ultrasound performed by an emergency physician in acute right iliac fossa pain. Crit Ultrasound J 10(1):31

Johansen I, Grimsmo A, Nakling J (2002) Ultrasonography in primary health care—experiences within obstetrics 1983–99. Tidsskr Nor Laegeforen 122(20):1995–1998

Bratland SZ, Eik-Nes SH (1985) Ultrasonic diagnosis of pregnant women in general practice. Tidsskr Nor Laegeforen 105(28):1940–1946

Eggebø TM, Dalaker K (1989) Ultrasonic diagnosis of pregnant women performed in general practice. Tidsskr Nor Laegeforen 109(29):2979–2981

Ornstein SM, Smith MA, Peggs J, Garr D, Gonzales J (1990) Obstetric ultrasound by family physicians. Adequacy as assessed by pregnancy outcome. J Fam Pract 30(4):403–408

Rodney WM, Prislin MD, Orientale E, McConnell M, Hahn RG (1990) Family practice obstetric ultrasound in an urban community health center. Birth outcomes and examination accuracy of the initial 227 cases. J Fam Pract 30(2):163–168

Brunader R (1996) Accuracy of prenatal sonography performed by family practice residents. Fam Med 28(6):407–410

Keith R, Frisch L (2001) Fetal biometry: a comparison of family physicians and radiologists. Fam Med 33(2):111–114

Bailey C, Carnell J, Vahidnia F, Shah S, Stone M, Adams M, Nagdev A (2012) Accuracy of emergency physicians using ultrasound measurement of crown-rump length to estimate gestational age in pregnant females. Am J Emerg Med 30(8):1627–1629

Saul T, Lewiss RE, Rivera MDR (2012) Accuracy of emergency physician performed bedside ultrasound in determining gestational age in first trimester pregnancy. Crit Ultrasound J 4(1):22

Shah S, Teismann N, Zaia B, Vahidnia F, River G, Price D, Nagdev A (2010) Accuracy of emergency physicians using ultrasound to determine gestational age in pregnant women. Am J Emerg Med 28(7):834–838

Stein JC, Wang R, Adler N, Boscardin J, Jacoby VL, Won G, Goldstein R, Kohn MA (2010) Emergency physician ultrasonography for evaluating patients at risk for ectopic pregnancy: a meta-analysis. Ann Emerg Med 56(6):674–683

Beals T, Naraghi L, Grossestreuer A, Schafer J, Balk D, Hoffmann B (2019) Point of care ultrasound is associated with decreased ED length of stay for symptomatic early pregnancy. Am J Emerg Med 37(6):1165–1168

Strommen J, Masullo L, Crowell T, Moffett P (2017) First-trimester vaginal bleeding: patient expectations when presenting to the emergency department. Mil Med 182(11):e1824–e1826

Everett CB, Preece E (1996) Women with bleeding in the first 20 weeks of pregnancy: value of general practice ultrasound in detecting fetal heart movement. Br J Gen Pract 46(402):7–9

Varner C, Balaban D, McLeod S, Carver S, Borgundvaag B (2016) Fetal outcomes following emergency department point-of-care ultrasound for vaginal bleeding in early pregnancy. Can Fam Physician 62(7):572–578

Shah S, Adedipe A, Ruffatto B, Backlund BH, Sajed D, Rood K, Fernandez R (2014) BE-SAFE: bedside sonography for assessment of the fetus in emergencies: educational intervention for late-pregnancy obstetric ultrasound. West J Emerg Med 15(6):636–640

Gottlieb M, Holladay D, Peksa GD (2019) Point-of-care ocular ultrasound for the diagnosis of retinal detachment: a systematic review and meta-analysis. Acad Emerg Med. https://doi.org/10.1111/acem.13682

Jacobsen B, Lahham S, Lahham S, Patel A, Spann S, Fox JC (2016) Retrospective review of ocular point-of-care ultrasound for detection of retinal detachment. West J Emerg Med 17(2):196–200

Lahham S, Shniter I, Thompson M, Le D, Chadha T, Mailhot T, Kang TL, Chiem A, Tseeng S, Fox JC (2019) Point-of-care ultrasonography in the diagnosis of retinal detachment, vitreous hemorrhage, and vitreous detachment in the emergency department. JAMA Netw Open 2(4):e192162

Ojaghihaghighi S, Lombardi KM, Davis S, Vahdati SS, Sorkhabi R, Pourmand A (2019) Diagnosis of traumatic eye injuries with point-of-care ocular ultrasonography in the emergency department. Ann Emerg Med. https://doi.org/10.1016/j.annemergmed.2019.02.001

Ojaghi Haghighi SH, Morteza Begi HR, Sorkhabi R, Tarzamani MK, Kamali Zonouz G, Mikaeilpour A, Rahmani F (2014) Diagnostic accuracy of ultrasound in detection of traumatic lens dislocation. Emergency 2(3):121–124

Barbic D, Chenkin J, Cho DD, Jelic T, Scheuermeyer FX (2017) In patients presenting to the emergency department with skin and soft tissue infections what is the diagnostic accuracy of point-of-care ultrasonography for the diagnosis of abscess compared to the current standard of care? A systematic review and meta-analysis. BMJ Open 7(1):e013688

Subramaniam S, Bober J, Chao J, Zehtabchi S (2016) Point-of-care ultrasound for diagnosis of abscess in skin and soft tissue infections. Acad Emerg Med 23(11):1298–1306

Gaspari R, Dayno M, Briones J, Blehar D (2012) Comparison of computerized tomography and ultrasound for diagnosing soft tissue abscesses. Crit Ultrasound J 4(1):5

Greenlund LJS, Merry SP, Thacher TD, Ward WJ (2017) Primary care management of skin abscesses guided by ultrasound. Am J Med 130(5):e191–e193

Mower WR, Crisp JG, Krishnadasan A, Moran GJ, Abrahamian FM, Lovecchio F, Karras DJ, Steele MT, Rothman RE, Talan DA (2019) Effect of initial bedside ultrasonography on emergency department skin and soft tissue infection management. Ann Emerg Med. https://doi.org/10.1016/j.annemergmed.2019.02.002

Lam SHF, Sivitz A, Alade K et al (2018) Comparison of ultrasound guidance vs. clinical assessment alone for management of pediatric skin and soft tissue infections. J Emerg Med 55(5):693–701

Gaspari RJ, Sanseverino A (2018) Ultrasound-guided drainage for pediatric soft tissue abscesses decreases clinical failure rates compared to drainage without ultrasound: a retrospective study. J Ultrasound Med 37(1):131–136

Gaspari RJ, Sanseverino A, Gleeson T (2019) Abscess incision and drainage with or without ultrasonography: a randomized controlled trial. Ann Emerg Med 73(1):1–7

Lin MJ, Neuman M, Rempell R, Monuteaux M, Levy J (2018) Point-of-care ultrasound is associated with decreased length of stay in children presenting to the emergency department with soft tissue infection. J Emerg Med 54(1):96–101

Costantino TG, Satz WA, Dehnkamp W, Goett H (2012) Randomized trial comparing intraoral ultrasound to landmark-based needle aspiration in patients with suspected peritonsillar abscess. Acad Emerg Med 19(6):626–631

Adhikari S, Blaivas M, Lander L (2011) Comparison of bedside ultrasound and panorex radiography in the diagnosis of a dental abscess in the ED. Am J Emerg Med 29(7):790–795

Levine MC, Arroyo A, Likourezos A, Homel P, Dickman E (2018) The use of point of care ultrasound in the evaluation of pediatric soft tissue neck masses. Am J Emerg Med. https://doi.org/10.1016/j.ajem.2018.10.048

Friedman N, Tseng F, Savic R, Diallo M, Fathi K, Mclean L, Tessaro MO (2019) Reliability of neck mass point-of-care ultrasound by pediatric emergency physicians. J Ultrasound Med. https://doi.org/10.1002/jum.14993

Friedman DI, Forti RJ, Wall SP, Crain EF (2005) The utility of bedside ultrasound and patient perception in detecting soft tissue foreign bodies in children. Pediatr Emerg Care 21(8):487–492

Oguz AB, Polat O, Eneyli MG, Gulunay B, Eksioglu M, Gurler S (2017) The efficiency of bedside ultrasonography in patients with wrist injury and comparison with other radiological imaging methods: a prospective study. Am J Emerg Med 35(6):855–859

Lee SH, Yun SJ (2018) Point-of-care wrist ultrasonography in trauma patients with ulnar-sided pain and instability. Am J Emerg Med 36(5):859–864

Gün C, Unlüer EE, Vandenberk N, Karagöz A, Sentürk GO, Oyar O (2013) Bedside ultrasonography by emergency physicians for anterior talofibular ligament injury. J Emerg Trauma Shock 6(3):195–198

Lee SH, Yun SJ (2017) The feasibility of point-of-care ankle ultrasound examination in patients with recurrent ankle sprain and chronic ankle instability: comparison with magnetic resonance imaging. Injury 48(10):2323–2328

Wu TS, Roque PJ, Green J, Drachman D, Khor K-N, Rosenberg M, Simpson C (2012) Bedside ultrasound evaluation of tendon injuries. Am J Emerg Med 30(8):1617–1621

Mohammadrezaei N, Seyedhosseini J, Vahidi E (2017) Validity of ultrasound in diagnosis of tendon injuries in penetrating extremity trauma. Am J Emerg Med 35(7):945–948

Vieira RL, Levy JA (2010) Bedside ultrasonography to identify hip effusions in pediatric patients. Ann Emerg Med 55(3):284–289

Cruz CI, Vieira RL, Mannix RC, Monuteaux MC, Levy JA (2018) Point-of-care hip ultrasound in a pediatric emergency department. Am J Emerg Med 36(7):1174–1177

Adhikari S, Blaivas M (2010) Utility of bedside sonography to distinguish soft tissue abnormalities from joint effusions in the emergency department. J Ultrasound Med 29(4):519–526

Gottlieb M, Holladay D, Peksa GD (2019) Point-of-care ultrasound for the diagnosis of shoulder dislocation: a systematic review and meta-analysis. Am J Emerg Med 37(4):757–761

Lee SH, Yun SJ (2019) Efficiency of knee ultrasound for diagnosing anterior cruciate ligament and posterior cruciate ligament injuries: a systematic review and meta-analysis. Skel Radiol. https://doi.org/10.1007/s00256-019-03225-w

Weinberg ER, Tunik MG, Tsung JW (2010) Accuracy of clinician-performed point-of-care ultrasound for the diagnosis of fractures in children and young adults. Injury 41(8):862–868

Riera A, Chen L (2012) Ultrasound evaluation of skull fractures in children: a feasibility study. Pediatr Emerg Care 28(5):420–425

Parri N, Crosby BJ, Glass C, Mannelli F, Sforzi I, Schiavone R, Ban KM (2013) Ability of emergency ultrasonography to detect pediatric skull fractures: a prospective, observational study. J Emerg Med 44(1):135–141

Rabiner JE, Friedman LM, Khine H, Avner JR, Tsung JW (2013) Accuracy of point-of-care ultrasound for diagnosis of skull fractures in children. Pediatrics 131(6):e1757–e1764

Choi JY, Lim YS, Jang JH, Park WB, Hyun SY, Cho JS (2018) Accuracy of bedside ultrasound for the diagnosis of skull fractures in children aged 0 to 4 years. Pediatr Emerg Care. https://doi.org/10.1097/PEC.0000000000001485

Parri N, Crosby BJ, Mills L, Soucy Z, Musolino AM, Da Dalt L, Cirilli A, Grisotto L, Kuppermann N (2018) Point-of-care ultrasound for the diagnosis of skull fractures in children younger than two years of age. J Pediatr 196:230–236.e2

Cross KP, Warkentine FH, Kim IK, Gracely E, Paul RI (2010) Bedside ultrasound diagnosis of clavicle fractures in the pediatric emergency department. Acad Emerg Med 17(7):687–693

Chien M, Bulloch B, Garcia-Filion P, Youssfi M, Shrader MW, Segal LS (2011) Bedside ultrasound in the diagnosis of pediatric clavicle fractures. Pediatr Emerg Care 27(11):1038–1041

Lee SH, Yun SJ (2019) Diagnostic performance of ultrasonography for detection of pediatric elbow fracture: a meta-analysis. Ann Emerg Med. https://doi.org/10.1016/j.annemergmed.2019.03.009

Rabiner JE, Khine H, Avner JR, Tsung JW (2015) Ultrasound findings of the elbow posterior fat pad in children with radial head subluxation. Pediatr Emerg Care 31(5):327–330

Chartier LB, Bosco L, Lapointe-Shaw L, Chenkin J (2017) Use of point-of-care ultrasound in long bone fractures: a systematic review and meta-analysis. CJEM 19(2):131–142

Hedelin H, Tingström C, Hebelka H, Karlsson J (2017) Minimal training sufficient to diagnose pediatric wrist fractures with ultrasound. Crit Ultrasound J 9(1):11

Rowlands R, Rippey J, Tie S, Flynn J (2017) Bedside ultrasound vs X-ray for the diagnosis of forearm fractures in children. J Emerg Med 52(2):208–215

Douma-den Hamer D, Blanker MH, Edens MA, Buijteweg LN, Boomsma MF, van Helden SH, Mauritz G-J (2016) Ultrasound for distal forearm fracture: a systematic review and diagnostic meta-analysis. PLoS ONE 11(5):e0155659

Sivrikaya S, Aksay E, Bayram B, Oray NC, Karakasli A, Altintas E (2016) Emergency physicians performed point-of-care-ultrasonography for detecting distal forearm fracture. Turk J Emerg Med 16(3):98–101

Tayal VS, Antoniazzi J, Pariyadath M, Norton HJ (2007) Prospective use of ultrasound imaging to detect bony hand injuries in adults. J Ultrasound Med 26(9):1143–1148

Neri E, Barbi E, Rabach I, Zanchi C, Norbedo S, Ronfani L, Guastalla V, Ventura A, Guastalla P (2014) Diagnostic accuracy of ultrasonography for hand bony fractures in paediatric patients. Arch Dis Child 99(12):1087–1090

Kozaci N, Ay MO, Akcimen M, Sasmaz I, Turhan G, Boz A (2015) The effectiveness of bedside point-of-care ultrasonography in the diagnosis and management of metacarpal fractures. Am J Emerg Med 33(10):1468–1472

Aksay E, Yesilaras M, Kılıc TY, Tur FC, Sever M, Kaya A (2015) Sensitivity and specificity of bedside ultrasonography in the diagnosis of fractures of the fifth metacarpal. Emerg Med J 32(3):221–225

Aksay E, Kilic TY, Yesılaras M, Tur FC, Sever M, Kalenderer O (2016) Accuracy of bedside ultrasonography for the diagnosis of finger fractures. Am J Emerg Med 34(5):809–812

Gungor F, Akyol KC, Eken C, Kesapli M, Beydilli I, Akcimen M (2016) The value of point-of-care ultrasound for detecting nail bed injury in ED. Am J Emerg Med 34(9):1850–1854

Kocaoğlu S, Özhasenekler A, İçme F, Pamukçu Günaydın G, Şener A, Gökhan Ş (2016) The role of ultrasonography in the diagnosis of metacarpal fractures. Am J Emerg Med 34(9):1868–1871

Kozaci N, Ay MO, Avci M, Turhan S, Donertas E, Celik A, Ararat E, Akgun E (2017) The comparison of point-of-care ultrasonography and radiography in the diagnosis of tibia and fibula fractures. Injury 48(7):1628–1635

Atilla OD, Yesilaras M, Kilic TY, Tur FC, Reisoglu A, Sever M, Aksay E (2014) The accuracy of bedside ultrasonography as a diagnostic tool for fractures in the ankle and foot. Acad Emerg Med 21(9):1058–1061

Tollefson B, Nichols J, Fromang S, Summers RL (2016) Validation of the Sonographic Ottawa Foot and Ankle Rules (SOFAR) study in a large urban trauma center. J Miss State Med Assoc 57(2):35–38

Ozturk P, Aksay E, Oray NC, Bayram B, Basci O, Tokgoz D (2018) The accuracy of emergency physician performed ultrasonography as a diagnostic tool for lateral malleolar fracture. Am J Emerg Med 36(3):362–365

Yesilaras M, Aksay E, Atilla OD, Sever M, Kalenderer O (2014) The accuracy of bedside ultrasonography as a diagnostic tool for the fifth metatarsal fractures. Am J Emerg Med 32(2):171–174

Kozaci N, Ay MO, Avci M, Beydilli I, Turhan S, Donertas E, Ararat E (2017) The comparison of radiography and point-of-care ultrasonography in the diagnosis and management of metatarsal fractures. Injury 48(2):542–547

Fagan TJ (1975) Letter: Nomogram for Bayes theorem. N Engl J Med 293(5):257

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Acknowledgements

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BS received a stipend from The Norwegian Committee on Research in General Practice, A board in Norwegian College of General Practitioners to work on the article. They requested broadly a systematic review on the use of ultrasound in general practice, but had no role in the design of the study nor in the collection, analysis, or interpretation of data and in writing the manuscript.

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Bjarte Sorensen

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Steinar Hunskaar

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BS is the corresponding author. Both BS and SH collaboratively conceived, designed the study, and wrote the manuscript. BS performed the search and screened the articles. Both authors read and approved the final manuscript.

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Bjarte Sorensen: BSc(Med) MB BS, Specialist in General Practice (Norwegian certification), Fellow of the Royal Australian College of General Practitioners (FRACGP), Hjelmeland General Practice Surgery, Prestagarden 13, 4130 Hjelmeland, Norway.

Steinar Hunskaar: MD PhD, Specialist in General Practice (Norwegian certification), Professor at the Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway and Vice Dean of Education at the Faculty of Medicine, University of Bergen. Senior Researcher at the National Centre for Emergency Primary Health Care, NORCE Norwegian Research Centre AS, Bergen, Norway.

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See Table  9 .

Ultrasound and general practice (MeSH terms)

“ultrasonography”[MeSH Terms] AND (“primary health care”[MeSH Terms] OR “general practice”[MeSH Terms] OR “general practitioners”[MeSH Terms] OR “physicians, primary care”[MeSH Terms] OR “physicians, family”[MeSH Terms])

Ultrasound and emergency medicine (MeSH terms)

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* To exclude indexed articles (which presumably were found by searching with MeSH terms) the keyword searches was done with the following filter:

((publisher[sb] NOT pubstatusnihms NOT pubstatuspmcsd NOT pmcbook) OR inprocess[sb] OR pubmednotmedline[sb] OR ((pubstatusnihms OR pubstatuspmcsd) AND publisher[sb])) OR pubmednotmedline[sb]

((publisher[sb] NOT pubstatusnihms NOT pubstatuspmcsd NOT pmcbook) OR pubmednotmedline[sb] OR ((pubstatusnihms OR pubstatuspmcsd) AND publisher[sb]))

inprocess[sb]

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Sorensen, B., Hunskaar, S. Point-of-care ultrasound in primary care: a systematic review of generalist performed point-of-care ultrasound in unselected populations. Ultrasound J 11 , 31 (2019). https://doi.org/10.1186/s13089-019-0145-4

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Review article, preclinical ultrasound imaging—a review of techniques and imaging applications.

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Ultrasound imaging is a well-established clinical imaging technique providing real-time, quantitative anatomical and physiological information in humans. The lack of ionizing radiation and relative low purchase and maintenance costs results in it being one of the most frequently used clinical imaging techniques with increasing use for guiding interventional clinical procedures. Until 20 years ago, translation of clinical ultrasound practices to preclinical applications proved a significant technological challenge due to the smaller size (25 g vs. 70 kg) and rapid conscious heart-rate (500–700 bpm vs. 60 bpm) of the mouse requiring an increase in both spatial and temporal resolution of 10–20-fold in order to achieve diagnostic information comparable to that achieved clinically. Since 2000 [ 1 ], these technological challenges have been overcome and commercial high frequency ultrasound scanners have enabled longitudinal studies of disease progression in small animal models to be undertaken. Adult, neonatal and embryonic rats, mice and zebrafish can now be scanned with resolutions down to 30 microns and with sufficient temporal resolution to enable cardiac abnormalities in all these species to be identified. In mice and rats, quantification of blood flow in cardiac chambers, renal, liver and uterine vessels, and intra-mural tissue movements can be obtained using the Doppler technique. Ultrasonic contrast microbubbles used routinely for clinical applications are now being further developed to include targeting mechanisms and drug-loading capabilities and the results in animal models bode well for translation for targeted drug delivery in humans.

Introduction

Although ultrasound has been used extensively since its development to study preclinical animal models much of the early work in this field was undertaken using transducers designed for ultrasound scanning of clinical small-parts or intra-operative imaging and operating in the frequency range between 10 and 20 MHz. Such frequencies enable images with spatial resolutions of the order of hundreds of microns to be acquired thus limiting their effectiveness in detecting abnormalities in smaller preclinical models. Additionally, clinical scanners designed to image the human heart with 60–100 beats per minute (bpm) had insufficient temporal resolution to image the rapid heart movement of preclinical models (400–600 bpm). The technological challenges of designing and manufacturing a commercial ultrasound scanner capable of resolving structures smaller than 100 microns and with sufficient temporal resolution to resolve cardiac motion within a mouse heart was overcome with the launch of the first commercially available preclinical ultrasound scanner in year 2000. Since then there has been a meteoric rise in the number of biology research publications using preclinical ultrasound imaging to assess adult, neonatal and embyronic rats, mice, and zebrafish with spatial resolutions approaching 30 micron and with frame-rates of up to 350 Hz achievable when imaging adult murine hearts enabling cardiac abnormalities to be identified. In addition, blood flow within cardiac chambers, renal, liver and uterine vessels can be measured in real-time using the Doppler function on the scanners and elastic properties of tissues can be measured using elastography techniques. New and exciting applications using ultrasonic contrast microbubbles designed to target specific biological markers and with drug-loading capabilities are being developed and tested in animal models. Technological advances in transducer manufacture has resulted in linear array transducers now replacing the first generation of mechanically-driven single-element transducers.

In this manuscript we will review the different imaging modes available on preclinical ultrasound scanners and highlight their utility for imaging of preclinical models. For clarity, the words preclinical animal model are used to describe small non-companion animals for which the genetic footprint can be modified and refers predominantly to mice, rats and zebrafish. All images and experiments described were performed under a UK Home Office Licence following ethical review by the University of Edinburgh.

Techniques of Ultrasound Imaging

Ultrasound waves are emitted from an ultrasound transducer. The choice of frequency of the transducer is important as higher frequencies give increased spatial resolution (i.e., smaller objects can be resolved) but the depth over which useful information can be obtained is reduced. For preclinical imaging, frequencies between 20 and 55 MHz are generally used with 15–20 MHz (image depth 3–4 cm) being used for adult rats, 30–40 MHz (image depth 10–20 mm) for adult mice and higher frequencies (up to 50 MHz, image depth 9 mm) used for neonatal mouse studies and embryonic and adult zebrafish imaging. When the transducer is coupled to the surface of the body using warmed ultrasound coupling gel, ultrasound images can be acquired in real-time. Ultrasound images are essentially two-dimensional (2D) cross-sectional slices through the body with the portion of anatomy closest to the transducer (generally the skin) displayed at the top of the screen and organs more distal displayed at depth. The depth at which organs are displayed on the screen is determined by the length of time the emitted ultrasound beam takes to return to the surface of transducer assuming a standard speed of sound in soft tissue of 1,540 ms −1 and assuming no multiple scattering has taken place. Unlike clinical ultrasound imaging in which scans are undertaken with the sonographer moving the transducer in real-time over the skin surface, for preclinical ultrasound scanning, the transducer is mounted in a probe-holder with 3D versatile movement enabling the probe to be oriented to any desired angle whilst avoiding small, but at high resolution, significant human movement compromising the quality of image acquisition. For almost all ultrasound imaging of preclinical models, the models are anesthetized prior to ultrasound scanning. With rats and mice, prior to ultrasound scanning, thick animal hair can be removed using electric hair clippers followed by the application of a depilatory cream to the scanning area. The use of the cream ensures that air bubbles are not trapped under any remaining hair stubble. Once the hair is removed, warmed coupling gel is placed on the body of the animal. Meanwhile, the temperature of the animal is recorded continuously especially in experiments where large amounts of the mouse hair has been removed. The probe is then lowered into the coupling gel. Due to the small size of preclinical models and their physical fragility, when scanning most organs, the ultrasound transducer does not touch the animal but scans through a thin layer of gel between the transducer head and the animal skin.

2D B-Mode Imaging

B-mode imaging or brightness-mode is the most commonly used mode in ultrasound imaging. In B-mode imaging 2D cross-sectional images of the animal are displayed in real-time on the screen. Images are acquired in transmit-receive mode where the transducer emits an ultrasound pulse, then pauses to receive signals back at the transducer which have been reflected and scattered from organ boundaries and parenchyma. This received signal is rapidly processed to form the gray-scale image displayed on the screen with highly reflective structures such as organ boundaries giving brighter (whiter) echoes and structures which scatter less ultrasound (e.g., blood) being darker. The focal position (highlighted as a yellow arrow in Figure 1 ) is the depth of optimal spatial resolution within the image. Using array probes, multiple focal zones can be selected but this will have a detrimental effect on the maximum frame-rate obtained. This may not be important for the more static abdominal organs but for cardiac imaging generally only one focal zone is used.

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Figure 1 . 2D B-mode image of a rat heart in diastole. Transducer used is 21 MHz center-frequency and focus of the beam is set at 15 mm depth. The dark zone running through the center of the image is caused by shadowing from the ribs.

Due to the rapid generation of ultrasound images, all scanners have the capability to freeze image acquisition and scroll (cine) through a pre-defined number of images in order to review the most recent acquisitions. Single images and short video clips can be saved on the scanner—the length of video clip is usually pre-set and tends to be longer for video clips acquired during echocardiographic studies and contrast imaging studies than for abdominal scans (see below).

M-Mode Imaging

M-mode imaging or motion-imaging is used principally to study fast moving structures such as heart-wall movement or valvular movement. A single line is selected in the B-mode image intersecting the chamber walls or valves of interest and ultrasound data is acquired only along the pre-selected M-mode line. Consequently data is acquired with high temporal resolution, as only one line of data is acquired rather than 128 lines of data in a full B-mode image. The M-mode data is displayed as a continuous function of time scrolling across the screen with depth on the y-axis and time on the x-axis ( Figure 2 ).

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Figure 2 . M-mode of mouse heart showing short-axis B-mode image in top half of image with M-mode line selected (yellow line in image). Lower image shows M-mode trace through the left ventricle at level of papillary muscles. Images acquired using a 40 MHz probe focussed at 9 mm depth.

Three-Dimensional (3D) and 4-Dimensional (4D) Imaging

Currently, three-dimensional preclinical ultrasound images are generated by the acquisition of consecutive B-mode ultrasound images acquired at discrete step sizes along a pre-determined path. Commercial software then reconstructs the 3D volume with elevational resolution dependent on the step size between consecutive B-mode image acquisitions ( Figure 3 ). For cardiac applications, images tend to be ECG and respiration-gated enabling accurate volumes of left ventricles to be determined which are not dependent on assumptions of the shape of the organs. In newer preclinical ultrasound scanners, complete 3D acquisitions are possible over a cardiac cycle (4D) enabling the dynamic movement of the heart to be viewed from any orientation. Acquisition times can be several minutes, dependent on the step-size between acquisition slices and relies upon good ECG and respiratory gating and high frame-rates. 3D imaging is also used to good effect in acquiring tumor volume data-sets, avoiding the need to make assumptions about the shape of tumor from a 2D image or the use of measurement calipers for superficial tumor volume assessment.

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Figure 3. (A) 2D B-mode image of an inguinal lymph node and (B) 3D volume of lymph node after 3D acquisition.

Doppler Techniques

Measurement of blood flow relies upon the use of the Doppler principle such that the measured change in frequency between a transmitted and received ultrasound beam is related to the velocity of the scatterers (red blood cells) from which the ultrasound beam is reflected.

Spectral Doppler

Spectral Doppler enables the Doppler frequency shift within a pre-selected region-of-interest (Doppler sample volume) to be displayed as a function of time. Most accurate measurements are made when the Doppler scatterers (red blood cells) are moving in the direction of the transmitted ultrasound beam. If the ultrasound beam cannot be aligned with the direction of blood flow, an angle correction can be made which attempts to compensate for this lack of alignment ( Figure 4 ).

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Figure 4 . Spectral Doppler trace with Doppler sample volume situated in center of left ventricle enables both inflow and outflow from the left ventricle to be measured with early (E) and late (atrial—A) waves and ejection time (ET) highlighted in the spectral Doppler trace. In addition isovolumic relaxation time (IVRT) and isovolumic contraction time (IVCT) may be measured where IVRT is equal to the time from the closure of the aortic valve to opening of mitral value and IVCT is the time of closure of mitral valve to opening of aortic valve.

Color Doppler

In Color Doppler mode, the mean velocity of scatterers (red blood cells) within a pre-selected region-of-interest are color-encoded and superimposed on the gray-scale B-mode image. In clinical applications blood moving away from the transducer tends to be encoded in shades of blue and blood moving toward the transducer in shades of red. For preclinical applications, color Doppler is especially useful for the rapid location of vessels ( Figure 5 ).

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Figure 5 . Color Doppler region of interest superimposed on 2D B-mode image of mouse liver. Color Doppler shows the vessel network—blue indicating movement of blood away from the transducer and red toward the transducer.

Power Doppler

In Power Doppler mode the power of the Doppler signal backscattered from red blood cells is displayed as a function of time within a pre-selected region of interest. The color is superimposed onto the gray-scale B-mode image. However, no directional information on blood flow is obtained but power Doppler is a more sensitive indicator of vascularity and thus useful in the detection of small vessels containing slower blood flow ( Figure 6 ).

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Figure 6 . 3D Power Doppler image of mouse testes. Imaged using 40 MHz probe.

Doppler Tissue Tracking

The Doppler principle can also be applied to quantify both inter-and intra- regional soft tissue movement in a technique known as tissue Doppler imaging . In this technique, the sample volume is placed within the moving tissue of interest, and the amplitude of the high-pass filter is reduced to enable slow, high-amplitude signals corresponding to tissue to be tracked [ 2 ]. By measuring the velocities between tissues regions, velocity gradients (rate of change of velocity with distance) and strain rate information can be calculated. However, tissue Doppler is only useful when the tissue motion is aligned with the direction of the ultrasound beam which has limitations in the assessment of cardiac radial function but has been used to good effect in studying mitral valve annulus movement.

Newer Imaging Techniques

Speckle tracking.

Alternative non-Doppler techniques such as speckle tracking can also be used to track tissue motion and as such are not reliant on alignment between beam and direction of movement. Speckle is effectively the fine background noise on ultrasound images. It is formed by the interference between echoes from structures which are smaller than the resolution of the ultrasound system. This interference pattern (speckle) is random and unique for any volume of tissue and although it may change with movement of the tissue, image processing techniques can be used to recognize and track the movement in 2D and 3D [ 3 ]. In order to use speckle tracking techniques, high frame-rates are required (>250 frames/s) with faster heart rates requiring higher frame-rates to ensure points of maximal and minimum strain and rate are captured. Using speckle tracking a range of parameters can be measured including displacement, velocity and strain and strain-rate.

Elastography Techniques

Ultrasound Elastography techniques are used to obtain information on the stiffness of tissue and can essentially be divided into those techniques which measure strain and those which measure shear wave velocity and from that directly measure Young's modulus (stress/strain). Strain elastography involves deformation of the tissue by application of a force (stress) and measuring the resulting degree of compression or extension of the tissue (strain) and comparing this to a reference soft tissue yielding a parameter known as the strain ratio. Since the magnitude of the stress applied is difficult to measure, strain elastography is not an intrinsic measure of tissue stiffness per se but the strain ratio can be used to infer tissue stiffness. Strain-rate is the change of tissue deformation with time. Both strain and strain-rate are routinely used in cardiac applications, where strain and strain-rate values from different regions of the myocardium can be compared. Strain analysis using ultrasound is generally performed using speckle tracking techniques whereby the speckle within different pre-selected ROIs (kernals) is tracked and the relative displacement between the two kernals can be measured. The distance between the two kernals, enables strain to be calculated and the variation of strain over time is strain-rate (s −1 ) [ 4 ] ( Figure 7 ).

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Figure 7 . Strain rate imaging of a nude mouse with MI as the result of ligation of left coronary artery. Top lhs is long-axis view of heart with arrows indicating direction and magnitude of movement of endocardial border. Bottom lhs shows change in volume of cavity over consecutive cardiac cycles alongside ECG and respiration. Top rhs shows radial strain-rate curves from five points selected on endocardial border while lower rhs shows longitudinal strain-rate curves from the same five points.

Alternatively, the measurement of shear wave velocity enables a quantitative measurement of Young's modulus of elasticity, E, provided that the tissue can be assumed to be incompressible (no change in density) and uniformly elastic ( Figure 8 ). The shear modulus G is related to the Young's modulus of elasticity E, by the following equation. E = 3G. Shear wave velocity, c s , generated as a result of a shearing force is given by, c s = √(G/ρ). By measuring the shear speed (usually between 1 and 10 m.s −1 ) and knowing the density, ρ, of the soft tissue (estimated at 1,000 kg.m −3 ), Young's modulus of elasticity can be calculated from the equation E = 3ρc s 2 . Hence measuring the shear speed can provide quantitative information on the elastic modulus. More detailed information on elastography techniques can be found in Hoskins [ 5 ] and Bamber et al. [ 6 ].

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Figure 8 . Shear wave elastography image of liver showing mean shear wave velocities and Young's modulus from a mouse liver (Reproduced with permission from S-Sharp Corporation).

Non-linear Imaging Techniques

Non-linear imaging techniques are utilized principally in the detection of ultrasonic contrast microbubbles (encapsulated gas bubbles). Contrast microbubbles when insonated with an ultrasound beam will begin to oscillate, expanding during the negative phase of the cycle and contracting during the positive phase. Dependent on the frequency and amplitude of the transmitted ultrasound the microbubbles can produce a significant non-linear backscattered signal without being destroyed. Since soft tissues predominantly scatter ultrasound in a linear manner by removing or canceling the linear component of the backscattered signal the kinetics and dynamic enhancement of organs can be visualized and quantified by measuring the increase in non-linear signal as a function of time. This can then be displayed in a variety of ways such as a maximum intensity projection sequence which will enable the dynamic filling patterns to be established within a region or as a graph illustrating the backscattered intensity kinetics within a region-of-interest ( Figure 9 ).

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Figure 9 . Contrast analysis of data-set acquired from right mouse kidney post ischemia-reperfusion (IRI) injury after tail-vein bolus injection of SonoVue. Mouse scanned in prone position. Multiple regions of interest (ROIs) can be drawn onto the image and the enhancement can be tracked as a function of time (bottom LHS). The relative enhancement of each ROI relative to pre-contrast image can be calculated and color-encoded (Top RHS).

Ultrafast Doppler

Novel imaging techniques such as ultrafast imaging and ultrafast Doppler techniques enable exquisitely detailed images and volumes of tumor vascularity to be built up even from vessels with very slow flow which are difficult to locate with standard Doppler techniques [ 7 ].

Preclinical Ultrasound—Cardiac Applications

The heart is probably the most challenging organ to image within the rodent due to its small size and rapid and complex motion. However, rodent models of cardiac diseases and myocardial infarction (MI) give valuable insights into anatomic and physiologic changes which are often directly aligned with changes observed in human cardiac disease and thus provide opportunities to assess novel therapeutic approaches and interventions.

Adult and neonatal cardiac scanning in mice, is routinely undertaken with the mouse in the supine position, hence the standard views obtained from mouse models are not exactly comparable to images acquired from clinical subjects who are scanned while lying in the left decubitus position. The ECG, respiration and temperature of the mouse are continuously recorded and monitored to ensure minimal variation throughout the scan-time. However, due to the range of mouse strains, anesthetic choice and depth there is a wide variation in accepted normal ranges of rodent cardiac indices. A recent review recommended standardized methods of measuring and reporting cardiac physiology in the adult murine model [ 8 ] and forms a useful step toward the introduction of standardized scanning procedures similar to those introduced by the American Society of Echocardiography and the European Association of Cardiovascular Imaging for clinical practice [ 9 ].

Similarly to clinical studies, all of the ultrasound imaging modalities: B-mode, M-mode, Doppler ultrasound and strain imaging can be used to assess cardiac function in mice.

Measurement of Cardiac Function in Adult Rodents

For adult mice scanning, transducer frequencies of 30–40 MHz are used, while for rats, ultrasound transducers operating between 10 and 25 MHz may be used—the higher frequencies for applications in smaller rats. To achieve high temporal resolution, only one focal position should be selected and placed at a depth commensurate with the region-of-interest.

There are two standard views used for initial assessment of the heart using parasternal 2D B-mode imaging —long-axis and short-axis views. Using these views initially provides a gross overview of the movement of left ventricular myocardial walls and mitral and aortic valve movements enabling areas of hyper-, hypo- or dyskinetic regions to be identified for further investigation. Due to the rapid heart-rate, cine-loops are generally acquired and can be reviewed at a much slower rate enabling key-points in the cardiac cycle such as systole and diastole to be identified. Alternatively a technique known as electrocardiogram-gated kilohertz visualization (EKV) can be used to investigate motion over one cardiac cycle with very high temporal resolution (1,000 frames/s). EKV scanning acquisition times are of the order of 30–60 s with the acquisition gated on the ECG and respiration cycles. Effectively sequential M-modes are acquired across the heart and temporally interleaved into a high temporal resolution 2D B-mode image data set of a cardiac cycle. Using this technique enables easier tracking of myocardial borders. Parameters that can be measured from B-mode or EKV images include stroke volume, ejection fraction, cardiac output, endocardial area, epicardial area, and percentage fractional myocardial area change. The formula and techniques used to measure these are beyond the scope of this review but can be found in Lang et al. [ 10 ].

M-mode is especially useful for the measurement of the maximum and minimum dimensions of the ventricles for calculation of cardiac indices such as fractional shortening and for the assessment of myocardial wall abnormalities ( Figure 2 ). However, M-mode measurements of chamber size should not be used for measurement of cardiac indices derived from volume measurements (e.g., ejection fraction) as these make assumptions re the shape of ventricles which are prone to error especially for animal models which have suffered myocardial infarctions and for which the shape of the ventricle can undergo deformation and remodeling. M-mode imaging can also provide information about valve movements with the M-mode line aligned with the tip of the mitral valve leaflets to study the thickness of the leaflets and valvular dynamics. Likewise for the aortic valve M-mode can be used to assess aortic valve cusp separation.

Four–dimensional imaging of the rodent heart is undertaken by acquiring multiple 2D EKV cineloops over a cardiac cycle. Gating on the ECG and respiration can be done either during acquisition or reconstruction of the 3D data-set. These cineloops are acquired at discrete, user-determined distances in either long- or short- axis views yielding a full 4D dataset. The cineloops are then temporally interleaved and reconstructed to allow the heart to be dynamically visualized over one cardiac cycle. 4D imaging enables the volume of cardiac chambers to be established with fewer inherent assumptions re the shape and dynamics of the chambers compared to calculations using 2D images ( Figure 10 ). As such calculation of indices requiring volume calculations, e.g., ejection fraction are more accurate and precise than measurements undertaken using 2D acquisitions [ 11 ].

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Figure 10 . LHS - 3D volume of murine left ventricle with aortic root. Images acquired at end-diastole. RHS 2D acquired images with endocardial borders of left ventricle highlighted in each slice.

Doppler measurements are used in echocardiography to measure blood flow across the mitral and aortic valves within the heart. With the Doppler sample volume sited at mid-ventricular level, in the apical 4-chamber view, mitral valve early (E) and late [atrial (A)] inflow velocities can be seen in the mitral spectral Doppler trace—the ratio of E/A and the deceleration time of the E-wave are indicators used in the assessment of diastolic function ( Figure 4 ). For some animals, separation of the E and A waves can be difficult to achieve due to the high heart-rates displayed by adult mice. However, isovolumic relaxation time can be measured along with systolic parameters such as ejection time and isovolumic contraction time enabling the calculation of myocardial performance index, an indicator of cardiac performance (see section on embryonic imaging).

Color Doppler is used in adult rodent echocardiography for the rapid assessment of blood flow within the chambers and specifically across valves. Constriction of valves can result in jetting which can be visualized as rapid flashes of color across the valves during contraction of chambers. This enables easier localization of the spectral Doppler sample volume within the jet to measure maximal velocities for assessment of constriction of valves. Color Doppler can also be used to localize small vessels. Figure 11 shows a duplex image (color and spectral Doppler) where color Doppler has being used to localize and identify the left anterior coronary artery and spectral Doppler enabling measurement of the velocities within the artery.

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Figure 11 . Blood flow within the left anterior descending coronary artery of a mouse model. Maximum velocity within the artery is 900 mm/sec.

Strain and Strain-Rate Imaging

Strain and strain-rate imaging are of specific value in rodent cardiac imaging providing information on regional myocardial deformation. Most commercial scanners use speckle tracking to determine strain (deformation)—by measuring the relative displacement of two kernals to determine strain and its variation over time to give strain-rate. In addition to a global strain parameter, radial, circumferential and longitudinal strain can be obtained providing information on regional segmental myocardial motion and systolic function. The timing of maximum and minimum strain and strain-rate values relative to systole and diastole can provide data on desynchronises between different myocardial regions especially relevant in infarct models ( Figure 7 ) [ 12 – 14 ].

Contrast Agents

Ultrasonic contrast agents used in preclinical studies for ultrasonic enhancement are composed of lipid-encapsulated gas-filled microbubbles which are injected via the tail-vein into the rodent. The agents are purely vascular agents, mixing freely with the blood. Limited enhancement is achieved using B-mode imaging, but in many instances this is sufficient to give enhancement of endocardial borders even at these high frequencies far removed from the resonant frequency of the microbubbles. Such enhancement enables better visualization and delineation of chamber volumes. The maximum recommended volume of contrast is 5 μl/g IV for rats but for mice a bolus injection of 50 μl is sufficient to see enhancement within the heart.

Measurement of Cardiac Function in Embryonic Mice

In embryonic mice and rats, the ultrasound backscattered signal from the circulating red blood cells is much greater than in adults. This is due to the nucleation of the red blood cells within the embryos and this enhancement can persist up to 3 to 4 days post-birth. This enhancement of the cardiac chambers, along with the complexities of determining the direction of blood flow within embryonic hearts and subsequent alignment of the Doppler beam along the direction of blood flow can make measurement of cardiac performance of embryos a challenging technique. In addition, since it is not possible to obtain an ECG from the embryos, the timing of diastole and systole is determined either by measurement of the movement of the myocardial walls or from the spectral Doppler waveform. Finally, the user needs to be mindful of the duration of anesthesia and its effect on both dam and embryos.

Since determination of the orientation of the heart can be challenging, even in older embryos, measurement of ratios calculated from the Doppler spectral trace will negate the angle dependence associated with aligning the Doppler beam with the direction of flow. Hence E/A ratios discussed above are useful indices to obtain although in embryos the A wave tends to be larger than the E wave. Likewise a parameter known as the myocardial performance (Tei) index which is a ratio of timing intervals determined from the spectral Doppler trace [summation of the isovolumic relaxation time (IVRT) and isovolumic contraction time (IVCT) divided by the ejection time (ET)] is useful and is largely unaffected by the angle of insonation. The myocardial performance is an indicator of overall cardiac performance with higher index values corresponding to an increasing dysfunctional heart. Strain rate imaging in embryonic mice is challenging and this may be due to the increased echogenicity of the blood pool, making speckle tracking more difficult.

Measurement of Cardiac Function in Neonatal Mice

Cardiac scanning of neonatal mice from day 1 post-partum (P1) is also possible. However, due to their small size and reduced hair-cover, care needs to be taken to ensure that they maintain body temperature (monitored using a neonatal rectal probe) throughout the scan. In addition, neonates can present anesthesia challenges and use of an adaptor and nose cone to ensure sufficient depth of anesthesia is recommended. In addition, dependent on the scanning table utilized, it is often necessary to use copper-tape to extend the electrodes to ensure a good ECG signal is obtained [ 15 ]. Ultrasound probes operating up to 50 MHz can be used to image early post-partum neonates and EKV scanning can be used to acquire high temporal and spatial resolution images.

Measurement of Cardiac Function in Zebrafish

The zebrafish ( Danio rerio ) has increasingly become an important tool in medical research [ 16 ], with significant application to the investigation of an extensive range of cardiovascular human diseases [ 17 ]. Its small size and corresponding small space requirements, relatively rapid sexual maturity (~3 months), generation of hundreds of embryos every week and external fertilization makes it increasingly one of the accessible animals for study.

The cardiac function of zebrafish can be imaged using preclinical ultrasound. The zebrafish heart is composed of 4 chambers—sinus venosus, atrium, ventricle and bulbus arteriosus. Light anesthesia can be induced for adult fish by injection of MS222 in the tank water. The fish can then be manipulated and placed on their dorsal side and gently restrained using plasticine that is lightly hand-molded around their bodies. Transducers up to 55 MHz can be used to image the hearts in both long and short axis views. Obtaining an ECG signal from adult zebrafish is challenging so the timing of systole and diastole is determined from cardiac chamber size and spectral Doppler traces with adult heart rates ranging from 120 to 180 beats/min. Additionally, the echogenicity of blood within adult zebrafish is similar to the surrounding tissue structures ( Figure 12 ) making the differentiation of chamber volumes challenging.

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Figure 12 . Spectral and color Doppler (Duplex) image of adult zebrafish heart.

Measurement of Cardiac Function in Embryonic Zebrafish

Assessment of cardiac function in embryonic zebrafish using ultrasound is also possible although the optical transparency of embryos means that cardiac function can also be studied using light microscopy techniques including video edge-detection techniques. Using Doppler ultrasound techniques, a rapid assessment of cardiac function can be undertaken with heart-rates in zebrafish embryos dependent on the temperature but at 28°C are around 200 bpm [ 18 ]. Before scanning, embryos are anesthetized in a petri-dish using MS222 and then embedded in agarose. Once the agar has set, fresh aquarium water is added to the dish to limit the effects of anesthesia. Individual embryonic fish can be then identified, and the orientation of their hearts noted using a stereomicroscope. The dish is then placed on top of a heated plate and temperature maintained at 28.5°C whilst scanning is being undertaken with a thermocouple placed adjacent to the embryo to monitor temperature. The ultrasound transducer is then lowered into the water and individual embryos may then be scanned ( Figure 13 ).

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Figure 13 . B-mode image of a 5 day-post-fertilization zebrafish embryo suspended in agar. Embryo imaged at 55 MHz.

Preclinical Ultrasound—Kidney Applications

The kidneys in a mouse can either be scanned with the mouse in supine or prone position. The hair can be removed firstly with electric hair clippers and then with depilatory cream. Unless contrast agents are being used, high temporal resolution is not required for imaging the kidneys so multiple focal positions can be selected across the depth of the kidney. Frequencies used tend be between 30 and 40 MHz dependent on the size of the animal. B-mode imaging is used to locate the kidney with the cortex of the kidney tending to have increased backscatter (brighter) compared to the central medulla. Both kidneys can be scanned in the adult rodent. Figure 14 shows an image of a mouse kidney and a duplex image using color Doppler to locate the vessel and direction of flow before placing the spectral Doppler sample volume within the vessel. Renal blood flow can be measured and the renal arterial resistive index calculated (peak systolic velocity—the end diastolic velocity) /peak systolic velocity) and its value indicative of the resistance to blood flow in the vascular bed [ 19 ].

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Figure 14. (A) B-mode image of kidney. Note the two focal positions on the image. (B) Duplex image of mouse kidney. In the Duplex image, the sample volume is localized using the color Doppler box as an indicator to show where the vessel lies and direction of blood flow.

Vascularity of the kidney can also be studied using ultrasonic contrast agents. When contrast is being used, the mouse is scanned in the prone position avoiding the potential of imaging artifacts caused by intestinal shadowing which can occur when the kidneys are scanned with the mouse in the supine position. Contrast agents are bolus-injected or infused using a syringe pump via the tail-vein. An injection of 50 μl Micromarker (Bracco Research SpA, Geneva, Switzerland) over a 5 second period of a 1:5 dilution is a typical dosing regimen. For acquisition, baseline images are acquired in contrast-specific imaging mode immediately prior to injection of the contrast agent and are saved either as a separate data-set or a temporal stamp is placed on the contrast image sequence indicating when contrast is injected and images taken prior to this time-stamp are considered baseline images. An alternative approach is to inject the contrast agent, then destroy the contrast agent within the 2D plane using a short, low-frequency high pressure acoustic pulse. The low-pressure contrast-specific imaging sequence is then reinstated, with the initial frames immediately after these high pressure pulses regarded as baseline images with subsequent frames displaying contrast enhancement. After contrast injection a long sequence of 2D images are obtained, the length of sequence can be pre-set by the user. Once the sequence has been saved, either in-house software or contrast-specific software developed by the manufacturers can be used to map the intensity of the backscattered signal within the regions-of-interest (eg medulla, cortex) to study the perfusion-dynamics. Metrics of interest include area-under-the curve, time-to-peak enhancement, wash-in rate and these can be used as indicators of blood volume and vessel density [ 20 ]. In many instances if an ischemic-reperfusion-injury (IRI) mouse model is being studied, one kidney can act as a control and both B-mode and contrast-enhancement data can then be acquired from both kidneys.

Preclinical Ultrasound—Liver Applications

The liver is a large organ within the mouse and consists of four lobes. To image the mouse liver, the mouse is again scanned in the supine position using insonating frequencies between 30 and 40 MHz ( Figure 15 ). B-mode ultrasound can be used to image all 4 lobes of the liver while ultrasound enables the portal vein and hepatic artery to be identified and blood velocities measured. Identification and sizing of tumors; staging of non-alcoholic fatty liver disease [ 21 ] and determination of fibrosis in the liver can also be achieved at preclinical frequencies. For the assessment of fibrosis in the liver, shear wave imaging techniques can also be used to measure the viscoelastic properties of mouse liver ( Figure 8 ) [ 22 ]. For preclinical imaging applications, shear waves are generally generated by a lower frequency 20 MHz radiation pulse and a 40 MHz probe used to measure the shear wave propagation within the liver tissue.

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Figure 15. (A) B-mode image of right lobe of normal mouse liver. Imaged using 40 MHz probe. (B) Color Doppler image of liver showing hepatic blood flow within the liver.

Preclinical—Ultrasound: Guided Injections

High-frequency ultrasound can also be used to guide injections into specific areas within the mouse anatomy. For injections into joints, this has recently been shown to have a higher success rate than using traditional anatomic landmarks [ 23 ]. Moreover, the less invasive approach of inducing infection within the uterus of a mouse using ultrasound-guided injections of lipopolysaccharide rather than through a mini-laparotomy clearly aligns with the principles of reduction, replacement and refinement which are central considerations for animal research [ 24 ]. Injections into fetal brains on externalized embryos, into adult kidneys and pancreas for orthotopic tumor cell injections and into the myocardium can all be undertaken.

Preclinical Ultrasound: Lymph Nodes

Due to their size and location, identification of lymph nodes using high frequency ultrasound can be difficult within the mouse model with many lying deep within the body, encapsulated in fat pads and some, such as the mesenteric lymph node, surrounded by the intestines. However, for cancer models it is important to locate the sentinel lymph node i.e., the node to which the primary tumor drains to first. To this end, both novel contrast agents [ 25 ] and novel ultrasound imaging techniques are under development to aid the detection of the location of this node [ 26 ].

Preclinical Ultrasound: Cranial

The use of ultrasound to study the development of the embryonic mouse brain in utero is well-established [ 27 , 28 ] with development of individual embryos tracked throughout gestation. However, the effects of attenuation and resultant aberrations in the ultrasound field caused by the skull in post-natal mice and rats tend to yield poor quality images resulting in the need for either a craniotomy or thinning of the skull to remove or reduce these effects. However in recent years, the use of high frequency transcranial ultrasound to study brain vasculature and cortex activation in non-anaethetised mice enabling longitudinal studies on post-natal brain development has been demonstrated [ 29 ]. The techniques utilized ultrafast (>500 Hz) compound Doppler techniques where the backscatter from multiple plane-wave emissions acquired at a range of angles are compounded. These early studies show in exquisite detail the future potential of using ultrasound for neuroscience applications.

The real-time nature of ultrasound, its small footprint in the preclinical laboratory and the inexpensive nature of ultrasound imaging compared to MRI and PET/CT, have made it a vital element within the preclinical imaging laboratory. However, the ease of image acquisition using ultrasound by non-specialist researchers has also resulted in a lack of rigor in the reporting of the scanning planes utilized to acquire measurements. This lack of rigor has resulted in a lack of consensus on the “normal” range of physiological values. The effect of heart-rate, temperature, type and depth of anesthesia also influence cardiac measurements and are essential to report in any study [ 30 , 31 ].

The vast increase in computing power has resulted in reductions in acquisition time of 3D volumes of organs and tumors and 4D acquisitions of the moving heart. Although these extra imaging dimensions will undoubtedly result in more accurate volume measurements it is not yet clear of their potential to provide additional diagnostic information. However, for the non-specialist user of ultrasound acquiring data in 3D enables visualization of structures more easily than from a single 2D imaging plane.

Although widely used within the clinical community, techniques such as strain, strain-rate and shear wave imaging are still gaining traction within the preclinical community. Strain and strain-rate values and the timing of their maximum values within the cardiac cycle may well prove useful as early indicators of myocardial dysfunction similar to that found in clinical studies. The use of shear wave imaging to measure fibrosis in the liver has been developed on one commercial preclinical platform. Certainly, the evidence is encouraging that these techniques can provide useful diagnostic information but more studies are required to validate this for preclinical rodent models and similarly to clinical studies there must be an understanding of the limitations of the technique [ 4 ].

Contrast agent development has been ongoing for the last 30 years with initial emphasis on the development of agents to highlight the ultrasound signal from vascular structures. Since contrast-specific imaging techniques rely on generating images based on the non-linear signal scattered from the microbubbles, a transducer of sufficient frequency bandwidth and sensitivity to these signals is required. At the frequencies used in clinical applications this is easily achieved (for a 4 MHz center frequency transducer, second harmonic is at 8 MHz) and transducers used for contrast imaging are usually sensitive up to at least the second harmonic i.e., twice the fundamental transmitted frequency. However, at preclinical frequencies, this is more challenging—in order to capture signals generated at the second harmonic, a much broader bandwidth transducer is required (20 MHz center frequency with second harmonics generated at 40 MHz and sub-harmonics at 10 MHz). Consequently, it tends to be the lower frequency preclinical transducers which have been optimized for contrast-specific imaging and thus, especially in mouse and zebrafish studies, there is an immediate reduction in spatial resolution when undertaking contrast studies. The development of capacitive micromachined ultrasound transducers (CMUTs) may provide a solution for higher resolution contrast microbubble work. CMUTS rely on a change in capacitance for generation of ultrasound rather than piezoelectricity and because they can be micromachined, lightweight 2D arrays are easily manufactured. In addition, they can be operated over a broad bandwidth and hence may be useful in the generation and detection of non-linear signals from contrast agents at higher frequencies necessary for optimal spatial resolution in preclinical animal models.

Super-resolution imaging can be used to generate very high resolution images. Using a sparse distribution of contrast microbubbles whereby single microbubbles are considered as point sources and over multiple ultrafast frame acquisitions composite images can be built up with resolution beyond the diffraction limit of the transmitted ultrasound [ 32 ]. Although the images require considerable post-processing, these images are exquisite in the detail. Improved computing power will improve the speed at which these images can be generated.

Although there is only one commercially available contrast agent manufactured for preclinical applications, lipid-encapsulated microbubbles can be made within the lab environment [ 33 ]. These microbubbles can be formulated to be used not only as contrast-enhancing agents but also as theranostic agents since targeting ligands can be relatively easily attached to the lipid shells and a drug payload incorporated within or loaded onto the microbubble shells. Although it is known that the drug payload can be released by insonation of the contrast microbubble by a high pressure acoustic pulse the translation of results obtained under highly controlled conditions in vitro have not yet been effectively translated to preclinical and clinical studies [ 34 ]. However, the development of mono-disperse microbubbles coupled with increasing access to the drive electronics within commercial preclinical scanners is likely to prompt new imaging sequences specifically tailored to these unique microbubble formulations and provide new and exciting theranostic applications.

Finally the use of artificial intelligence (AI) is an exciting area of research undergoing evaluation in the clinical ultrasound workload pipeline. Within clinical ultrasound imaging, AI is currently being evaluated for automatic feature detection, image optimization and quantification. Within the preclinical ultrasound imaging community, AI is now incorporated in one preclinical ultrasound platform to automatically define boundaries and complete left ventricular functional measurements [ 35 ]. Although the results suggested that the quality of ultrasound images acquired was a limiting factor for AI quantification, for the non-specialist preclinical ultrasound user AI is likely to make scanners simpler to use, make image analysis easier and more rapid to implement.

In this review article, a range of applications utilizing preclinical ultrasound imaging techniques have been discussed. However, this list is not exhaustive. The range of preclinical applications for which ultrasound imaging is capable of providing meaningful diagnostic information is likely to rapidly increase over the next decade as these scanners become embedded technology within biology laboratories. The increasing use of AI and the use of contrast microbubble formulations allied with unique driving and detection mechanisms will ensure that preclinical ultrasound remains a versatile and cost-effective tool.

Author Contributions

CM wrote the original manuscript. AT reviewed the manuscript and acquired almost all the images.

This work was supported by The Wellcome Trust - Grant Number 212923/Z/18/Z.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

1. Foster FS, Pavlin CJ, Harasiewicz KA, Christopher DA, Turnbull DH. Advances in ultrasound biomicroscopy. Ultrasound Med Biol. (2000) 26:1–27. doi: 10.1016/S0301-5629(99)00096-4

PubMed Abstract | CrossRef Full Text | Google Scholar

2. Polito MV, Stoebe S, Galasso G, De Rosa R, Citro R, Piscione F, et al. Analysis of regional right ventricular function by tissue Doppler imaging in patients with aortic stenosis. J Cardiovasc Echogr. (2019) 29:111–8. doi: 10.4103/jcecho.jcecho_27_19

3. McDicken WN, Thomson A, White A, Toor I, Gray G, Moran CM, et al. 3D angle-independent Doppler and speckle tracking for the myocardium and blood flow. Echo Res Pract. (2019) 6:105–14. doi: 10.1530/ERP-19-0040

4. Amzulescu MS, de Craene M, Langet H, Pasquet A, Vancraeynest D, Pouleur AC, et al. Myocardial strain imaging: review of general principles, validation, and sources of discrepancies. European Heart Journal – Cardiovasc Imag . (2019) 20:605–19. doi: 10.1093/ehjci/jez041

5. Hoskins PR. Principles of ultrasound elastography. Ultrasound . (2012) 20:8–15. doi: 10.1258/ult.2011.011005

CrossRef Full Text | Google Scholar

6. Bamber J, Cosgrove D, Dietrich CF, Fromageau J, Bojunga J, Calliada F, et al. EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography. Part 1: Basic principles and technology. Ultraschall Med . (2013) 34:169–84. doi: 10.1055/s-0033-1335205

7. Demene C, Payen T, Dizeux A, Barrois G, Gennisson J-L, Bridal L, et al. 3-D longitudinal imaging of tumor angiogenesis in mice in vivo using ultrafast Doppler tomography. Ultrasound Med Biol . (2019) 45:1284–96. doi: 10.1016/j.ultrasmedbio.2018.12.010

8. Lindsey ML, Kassiri Z, Virag JAI, de Castro Bras LE, Shcerrer-Crosbie M. Guidelines for measuring cardiac physiology in mice. Am J Physiol Heart Circ Physiol . (2018) 314:H733–52. doi: 10.1152/ajpheart.00339.2017

9. Nagueh SF, Smiseth OA, Appleton CP, Byrd IIIBF, Dokainish H, Edvardsen T, et al. Recommendations for the evaluation of left ventricular diastolic function by echocardiography: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echo . (2016) 29:277–314. doi: 10.1016/j.echo.2016.01.011

10. Lang RM, Badano LP, Mor-Avi V, Afilalo J, Armstrong A, Ernande L, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr . (2015) 28:1–39. doi: 10.1016/j.echo.2014.10.003

11. Damen FW, Berman AG, Soepriatna AH, Ellis JM, Buttars SD, Aasa KL, et al. High-frequency 4-Dimensional ultrasound (4DUS): a reliable method for assessing murine cardiac function. Tomography . (2017) 3:180–7. doi: 10.18383/j.tom.2017.00016

12. Bhan A, Sirker A, Zhang J, Protti A, Catibog N, Driver W, et al. High-frequency speckle tracking echocardiography in the assessment of left ventricular function and remodelling after murine myocardial infarction. Am J Physiol Heart Circ Physiol . (2014) 306:H1371–83. doi: 10.1152/ajpheart.00553.2013

13. Boyle JJ, Soepriatna A, Damen F, Rowe RA, Pless RB, Kovacs AGoergen CJ, et al. Regularization-free strain mapping in three dimensions, with applications to cardiac ultrasound. J Biomed Eng . (2019) 141:011010–11. doi: 10.1115/1.4041576

14. Schnelle M, Caitbog N, Zhang M, Nabeebaccus AA, Anderson G, Richards DA, et al. Echocardiographic evaluation of diastolic function in mouse models of heart disease. J Mol Cell Cardiol . (2018) 114:20–8. doi: 10.1016/j.yjmcc.2017.10.006

15. Castellan RFP, Thomson A, Moran CM, Gray GA. Longitudinal assessment of cardiac structural and functional maturation and regeneration following injury in the neonatal mouse using electrocardiogram-gated high-resolution ultrasound. Ultrasound Med Biol . (2020) 46:167–79. doi: 10.1016/j.ultrasmedbio.2019.09.012

16. Lieschke GJ, Currie PD. Animal models of human disease: zebrafish swim into view. Nat Rev Genet . (2007) 8:353–67. doi: 10.1038/nrg2091

17. Wang LW, Hutter IG, Santiago CF, Kesteven SH, Yi Z-Y, Feneley MP, et al. Standardized echocardiographic assessment of cardiac function in normal adult zebrafish and heart disease models. Dis Model Mech . (2017) 10:63–76. doi: 10.1242/dmm.026989

18. Gierten J, Pylatiuk C, Hammouda O, Schock C, Stegmaier J, Wittbrodt J, et al. Automated high-throughput heartbeat quantification in medaka and zebrafish embryos under physiological conditions. Sci Rep . (2020) 10:2046. doi: 10.1038/s41598-020-58563-w

19. Abe M, Akaishi T, Miki T, Miki M, Funamizu Y, Araya K, et al. Influence of renal function and demographic data on intrarenal Doppler ultrasonography. PLoS ONE . (2019) 14:e0221244. doi: 10.1371/journal.pone.0221244

20. Liang S, Gao Y, Liu Y, Qiu C, Chen Y, Zhu S. Contrast-enhanced ultrasound in evaluating of angiogenesis and tumour staging of nasophyryngeal carcinoma in nude mice. PLoS ONE . (2019) 14:e0221638. doi: 10.1371/journal.pone.0221638

21. Fernandez-Dominguez I, Echevarria-Uraga JJ, Gomez N, Luka Z, Wager C, Lu SC, et al. High-frequency ultrasound imaging for longitudinal evaluation of non-alcoholic fatty liver progression in mice. Ultrasound Med Biol . (2011) 37:1161–9. doi: 10.1016/j.ultrasmedbio.2011.04.012

22. Yeh C-Y, Chen B-R, Kuo P-L, Li P-C. In vivo measurement of liver elasticity on mice using a single element preclinical ultrasound system. IEEE Trans Ultrason Ferroelectr Freq Control . (2015) 62:1295–307. doi: 10.1109/TUFFC.2014.006953

23. Ruiz A, Bravo D, Duarte A, Adler RS, Raya JG. Accuracy of ultrasound-guided versus landmark-guided intra-articular injection for rat knee joints. Ultrasound Med Biol . (2019) 45:2787–96. doi: 10.1016/j.ultrasmedbio.2019.06.403

24. Rinaldi SF, Makieva S, Frew L, Wade J, Thomson A, Moran CM, et al. Ultrasound-guided intrauterine injection of lipopolysaccharide as a novel model of preterm birth in the mouse. AM J Pathol . (2015) 185:1201–6. doi: 10.1016/j.ajpath.2015.01.009

25. Yoon H, Yarmoska SK, Hannah AS, Yoon C, Hallam KA, Emelianov SY. Contrast-enhanced ultrasound imaging in vivo with laser-activated nanodroplets. Med Phys . (2017) 44:3444–9. doi: 10.1002/mp.12269

26. Evertsson M, Kjellmann P, Cinthio M, Andersson R, Tran TA, Zandt R, et al. Combined magnetomotive ultrasound, PET/CT, and MR imaging of 68Ga-labelled superparamagnetic iron oxide nanoparticles in rat sentinel lymph nodes. Sci Rep . (2017) 7:4824. doi: 10.1038/s41598-017-04396-z

27. Aristizabal O, Mamou J, Ketterling JA, Turnbull DH. High-throughput, high-frequency 3-D ultrasound for in utero analysis of embryonic mouse brain development. Ultrasound Med Biol . (2013) 39:2321–32. doi: 10.1016/j.ultrasmedbio.2013.06.015

28. Autuori MC, Pai YJ, Stuckey DJ, Savery D, Marconi AM, Massa V, et al. Use of high-frequency ultrasound to study the prenatal development of cranial neural tube defects and hydrocephalus in Gldc-deficient mice. Prenat Diagno . (2017) 37:273–81. doi: 10.1002/pd.5004

29. Tiran E, Ferrier J, Deffieux T, Gennisson JL, Pezet S, Lenkei Z, et al. Transcranial functional ultrasound imaging in freely moving awake mice and anesthetized young rats without contrast agent. Ultrasound Med Biol. (2017) 43:1679–89. doi: 10.1016/j.ultrasmedbio.2017.03.011

30. Stout D, Berr SS, LeBlanc A, Kalen JD, Osbourne D, Price J, et al. Guidance for methods descriptions used in preclinical imaging papers. Mol Imag . (2013) 12:1–15. doi: 10.2310/7290.2013.00055

31. Pachon RE, Scharf BA, Vatner DE, Vatner SF. Best anesthetics for assessing left ventricular systolic function by echocardiography in mice. Am J Physiol. (2015) 308:H1525–9. doi: 10.1152/ajpheart.00890.2014

32. Errico C, Pierre J, Pezet S, Desailly Y, Lenkei Z, Couture O, et al. Ultrafast ultrasound localization microscopy for deep super-resolution vascular imaging. Nature . (2015) 527:499–502. doi: 10.1038/nature16066

33. Owen J, Kamila S, Shrivastava S, Carugo D, de la Serna JB, Mannaris C, et al. The role of PEG-40-sterate in the production, morphology and stability of microbubbles. Langmuir . (2019) 35:10014–24. doi: 10.1021/acs.langmuir.8b02516

34. Roovers S, Segers T, Lajoinie G, Deprez J, Versluis M, de Smedt SC, et al. The role of ultrasound-driven microbubble dynamics in drug delivery: from microbubble fundaments to clinical translation. Langmuir . (2019) 35:10173–91. doi: 10.1021/acs.langmuir.8b03779

35. Grune J, Ritter D, Kraker K, Pappritz K, Beyhoff N, Schutte T, et al. Accurate assessment of LV function using the first automated 2D-border detection algorithm for small animals -evaluation and application to models of LV dysfunction. Cardiovasc Ultrasound . (2019) 17:7. doi: 10.1186/s12947-019-0156-0

Keywords: ultrasound, preclinical, mouse model, rat model, zebrafish

Citation: Moran CM and Thomson AJW (2020) Preclinical Ultrasound Imaging—A Review of Techniques and Imaging Applications. Front. Phys. 8:124. doi: 10.3389/fphy.2020.00124

Received: 29 November 2019; Accepted: 30 March 2020; Published: 05 May 2020.

Reviewed by:

Copyright © 2020 Moran and Thomson. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Carmel M. Moran, carmel.moran@ed.ac.uk

This article is part of the Research Topic

Status Go for Preclinical Imaging

ScienceDaily

Scientist shows focused ultrasound can reach deep into the brain to relieve pain

Research reveals potential of using low-intensity focused ultrasound for pain management.

You feel a pain, so you pop a couple of ibuprofen or acetaminophen. If the pain is severe or chronic, you might be prescribed something stronger -- an opioid pain killer that can be addictive under some circumstances.

But what if you could ease pain by non-invasively manipulating a spot inside your brain where pain is registered?

A new study by Wynn Legon, assistant professor at the Fralin Biomedical Research Institute at VTC, and his team points to that possibility. The study, published in the journal PAIN today (Monday, Feb. 5), found soundwaves from low-intensity focused ultrasound aimed at a place deep in the brain called the insula can reduce both the perception of pain and other effects of pain, such as heart rate changes.

"This is a proof-of-principle study," Legon said. "Can we get the focused ultrasound energy to that part of the brain, and does it do anything? Does it change the body's reaction to a painful stimulus to reduce your perception of pain?"

Focused ultrasound uses the same technology used to view a baby in the womb, but it delivers a narrow band of sound waves to a tiny point. At high intensity, ultrasound can ablate tissue. At low-intensity, it can cause gentler, transient biological effects, such as altering nerve cell electrical activity

Neuroscientists have long studied how non-surgical techniques, such as transcranial magnetic stimulation, might be used to treat depression and other issues. Legon's study, however, is the first to target the insula and show that focused ultrasound can reach deep into the brain to ease pain.

The study involved 23 healthy human participants. Heat was applied to the backs of their hands to induce pain. At the same time, they wore a device that delivered focused ultrasound waves to a spot in their brain guided by magnetic resonance imaging (MRI).

Participants rated their pain perception in each application on a scale of zero to nine. Researchers also monitored each participant's heart rate and heart rate variability -- the irregularity of the time between heart beats -- as a means to discern how ultrasound to the brain also affects the body's reaction to a painful stimulus.

Participants reported an average reduction in pain of three-fourths of a point.

"That might seem like a small amount, but once you get to a full point, it verges on being clinically meaningful," said Legon, also an assistant professor in the School of Neuroscience in Virginia Tech's College of Science. "It could make a significant difference in quality of life, or being able to manage chronic pain with over-the-counter medicines instead of prescription opioids."

The study also found the ultrasound application reduced physical responses to the stress of pain -- heart rate and heart rate variability, which are associated with better overall health.

"Your heart is not a metronome. The time between your heart beats is irregular, and that's a good thing," Legon said. "Increasing the body's ability to deal with and respond to pain may be an important means of reducing disease burden."

The effect of focused ultrasound on those factors suggests a future direction for the Legon lab's research -- to explore the heart-brain axis, or how the heart and brain influence each other, and whether pain can be mitigated by reducing its cardiovascular stress effects.

Other authors on the paper include Andrew Strohman, an M.D.+Ph.D. student in the Virginia Tech Carilion School of Medicine and Virginia Tech's Translational Biology, Medicine, and Health program, and other Legon Lab members.

The study was supported by the Seale Innovation Fund, the Focused Ultrasound Foundation, and the National Institutes of Health.

  • Pain Control
  • Medical Devices
  • Fibromyalgia
  • Brain Injury
  • Brain-Computer Interfaces
  • Medical Technology
  • Echocardiography
  • Gate control theory of pain
  • Chronic pain
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Materials provided by Virginia Tech . Original written by Matt Chittum. Note: Content may be edited for style and length.

Journal Reference :

  • Wynn Legon, Andrew Strohman, Alexander In, Brighton Payne. Noninvasive neuromodulation of subregions of the human insula differentially affect pain processing and heart-rate variability: a within-subjects pseudo-randomized trial . Pain , 2024; DOI: 10.1097/j.pain.0000000000003171

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A wearable ultrasound patch

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Wearable technologies are advancing rapidly and can provide a multitude of skin-based physical and chemical readouts. However, harnessing wearable technologies for internal imaging applications such as ultrasound – which provides crucial information on organ function and disease – has been challenging.

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A Systematic Review of the Clinical Efficacy of Micro-Focused Ultrasound Treatment for Skin Rejuvenation and Tightening

1 Medicine, Mayo Hospital Lahore, Lahore, PAK

Nabiha Khalid

2 Biochemistry, University of Gujrat, Gujrat, PAK

The demand for non-invasive skin-tightening techniques is continuously on the rise, as now numerous patients seek safe and effective alternative body, neck, and facial aesthetic surgical procedures. Micro-focused ultrasound (MFU) has been recently introduced as a novel energy modality for skin rejuvenation to produce a more significant wound healing response at various levels, including strong collagen remodeling and long-lasting clinical response. This literature study was intended to find the role and efficiency of using micro-focused ultrasound therapy in male and female patients aged 35-65. A total of 139 articles were extracted from the PubMed and Science Direct electronic databases. After a thorough evaluation and following the exclusion and inclusion criteria, 10 full-text articles were relevant to the study. The goal was to analyze and examine the effects and benefits of MFU treatment to improve the skin. In addition, all of the patients were evaluated to report the harms and risks associated with MFU treatment. The literature study results revealed that significant improvements in the overall aesthetics of sagging of the mid and lower face could be accomplished by using a micro-focused ultrasonic treatment plan. Patients report no considerable side effects, and the results were also long-lasting. MFU treatment can activate deeper tissues without causing injury to the epidermis, which sets it apart from all other skin tightening methods. Better improvements rates have been reported by both patients' self-assessment and clinical investigators' evaluation.

Introduction and background

Surgical lifting procedures have typically been used to treat facial and neck skin sagging and laxity. However, a broad range of nonsurgical procedures has emerged as an alternative to surgery over the last decade. Through the administration of controlled dermal heating, treatments, including fractional and ablative laser skin resurfacing and radiofrequency (RF), offer varying tissue tightening levels.

Traditional ablative laser skin rejuvenation is associated with a lengthy healing period and the possibility of delayed dyspigmentation [ 1 ]. Additionally, heat penetration up to 2-4 mm into the skin is needed to achieve minor skin tightening produced by RF devices. Thus, it promotes healing wounds and neocollagenesis without causing epidermal damage or clinical recovery [ 2 ]. When compared to ablative laser skin rejuvenating or surgical face lifting procedures, the advantages of this method are indistinct: minimal downtime, relative safety for usage on non-facial areas and skin color, and a favorable side effect profile [ 3 ]. Unfortunately, less intrusive procedures have a history of poor efficacy, uneven clinical outcome, and a shorter-lasting tightening effect.

Studies reported that the acoustical energy of high-intensity focused ultrasound (HIFU) is considered to penetrate tissue far deeper than laser or RF radiation. And these have recently been developed to treat subcutaneous lipolysis [ 4 ]. Ultrasound waves penetrate tissue, causing molecules to vibrate at just the focus of the beam. So at the focal point of the beam, friction among tissue molecules creates thermal damage. The depth of penetration is determined by the frequency of the waves, with higher frequency waves generating a lower focal injury zone. In contrast, shallow frequency waves generate focal thermal injury zones (TIZs) across deeper layers [ 5 ].

Micro-focused ultrasound (MFUS) was introduced in 2009 to offer precision-focused thermal injury zones at therapeutic depths larger than those available with the previous technologies [ 6 ]. In addition, it is capable of delivering deep heat energy into the superficial dermis and subdermal connective tissue at tissue planes to induce more extensive collagen remodeling [ 7 ]. That's why the MFUS device may be ideally adapted to treat the problem of skin laxity.

MFUS, in opposed to HIFU, offers more accurate energy delivery due to advancements in the system that better meet the needs of skin laxity [ 8 ]. Previous studies indicated that variations in small durations of pulse combined with greater frequency transducers enable MFUS to produce specific areas of coagulative necrosis, known as TIZs, for transcutaneous therapy. Every TIZ is precisely concentrated at a specific depth and heated with smaller pulses (150 ms) to induce shallow zones (1 mm 3 ) of coagulative necrosis at the location. However, the superficial layers and surrounding tissue mostly remain unaffected. The thermal harm is limited, much like a laser pulse, by maintaining the pulse duration small [ 8 - 9 ].

Moreover, as long as the energy supplied does not exceed the frequency and focal depth radiated for a particular transducer, the epidermal surface is kept undisturbed. This thus removes the requirement for shallow cooling and expediting the retrieval procedure, as healing proceeds quickly from untreated neighboring tissue [ 9 - 10 ]. The MFUS approach can reach deeper into tissue than its nonsurgical counterparts. Engaging the superficial musculoaponeurotic system (SMAS) achieves more excellent tissue tightness and benefits that last longer. The SMAS runs superficially to engage with the dermis and goes deep into the subcutaneous fat. It surrounds the muscles of facial expression and lies deeper in the subcutaneous fat. The SMAS layer, like the dermal layer of the skin, is made up of collagen and elastic fibers, but it has a more lasting retention ability and compared to the skin alone, shows less delayed relaxation following lifting procedures [ 11 ]. As a result, the SMAS is a reported great target for non-invasive skin tightening.

MFU causes an immediate contraction of denatured collagen through heat stimulation, triggers neocollagenesis, and collagen remodeling with subsequent skin tightening. It accomplishes this by establishing tiny, precisely regulated thermal coagulation sites in the mid to deep reticular dermis, all the way up to the superficial muscular aponeurotic system (SMAS) [ 12 ]. The Food and Drug Administration (FDA) has approved using an MFU device (Ulthera, Ulthera Inc., Mesa, Arizona) to raise the tissues in the brow, neck, and submentum without invasive surgery. The Ulthera system is an MFU device that is used for this purpose. Micro-focused ultrasound (MFU) therapy is combined with high-resolution ultrasound imaging to transfer energy to exact depths (up to 5 mm) inside the skin's dermal layers and SMAS while protecting the epidermal layers. The Ulthera system encourages the introduction of new tissue as well as collagen and elastin remodeling by modulating thermally induced tissue contraction and a wound-healing response. The heat is contained within small focal patches of the dermis, avoiding the epidermis and surrounding tissue [ 13 ].

Methodology

The inclusion and exclusion criteria of this study are listed in Table ​ Table1 1  [ 14 ].

Search strategies

For the collection of data, the search was performed using the PubMed and Science Direct electronic databases. The Google Scholar platform was used for article downloading and citation. The research papers were selected from the year 2013 to 2021. To search required studies and articles, MeSH terms were employed for PubMed to determine the best and optimal suited keywords. The focus keywords for search purposes were "Micro Focused Ultrasound," "Skin Rejuvenation," and "Skin Laxity Treatment." Only human studies were included, and any clinical trials on animals and other non-humanized models were excluded. While searching from Science Direct, the search method was optimized to select only those papers that contain the required keywords in the title or the abstract. The same technique opted for the PubMed search. Furthermore, the option to exclude non-humanized trials was not available on Science Direct; each publication was manually verified to ensure that only human studies were included for review writing purposes. The articles in the Bibliography section of selected articles were also searched for full text.

Result of the data search

The search strategy on micro-focused ultrasound for skin improvement recommended 80 articles on PubMed and 59 papers on Science Direct. The total number of articles thus found was 139. After cross-checking and comparing the titles of articles, irrelevant and repeated articles were excluded from the search. So from a total of 139 articles, 100 were found to be irrelevant to the targeted search and thus were eliminated. The remaining number of articles after this step was 39. After studying the abstract of these articles, 10 were discarded. The remaining 19 articles were further thoroughly studied and investigated to find whether they meet the inclusion criteria or not. Ten of these articles didn't follow the inclusion criteria, so they were also eliminated. Finally, one article was further selected after cross-checking the bibliography of already selected articles and was included too. In the end, 10 articles that entirely meet the inclusion criteria were finally selected for review writing (Figure ​ (Figure1) 1 ) [ 14 ].

An external file that holds a picture, illustration, etc.
Object name is cureus-0013-00000020163-i01.jpg

Results and discussion

Murad Alam et al. conducted the initial clinical research to determine if MFU-V might raise the brow during the treatment of the whole neck and face through the application of micro-focused ultrasound [ 14 ]. MFU-V was applied on the temples, submental region, cheeks, side of the head, and forehead using three transducers. These were used to emit 4 MHz and 7 MHz thermal energy at focal depths of 4.5 mm and 3.0 mm, respectively. A total of 36 people (34 females) were enrolled for this study, with one subject dropping out and 35 being evaluated. The average age was 44 years old (range 32-62). The evaluators considered 30 of 35 individuals (86%) to have a clinically significant brow-lift 90 days following treatment (P =.00001). As measured by pictures at 90 days, the average change in eyebrow height was 1.7 mm, as per the second primary outcome measure [ 14 ].

Several studies have found that using numerous micro-focused ultrasound treatment sessions improves the efficacy of the skin rejuvenation process [ 15 ]. For example, in one study, Sasaki et al. used a 4 MHz 4.5 mm transducer. Following that, a 7 MHz 3.0 mm transducer was used to treat the neck and face regions. According to two blinded doctors, eight out of 10 evaluable patients demonstrated therapeutic benefit 90 days following therapy while nine subjects claimed improvement [ 16 ]. Another study by Fabi et al. investigated the effectiveness of MFU-V therapy at one or two treatment depths, the effect of changing the orientation and number of treatment lines, and the total energy applied during the treatment procedure. They discovered that 15 vertically oriented treatment lines with tissue depths of 4.5 mm and 3.0 mm significantly raised oppositional marionette lines and brows compared to 15 horizontally oriented treatment lines [ 17 ]. In general, the combination of treatment lines and increased energy at dual depths resulted in much more lifting in areas receiving treatment lines.

In research by Shome et al., Ulthera was used to treat 50 adult Indian individuals with sagging in their midface and lower face. The participants were treated with Ulthera 3.0 mm probes that targeted the deep dermis and 4.5 mm probes that targeted the superficial muscular aponeurotic system. Allergic responses and adverse effects, such as scarring and nerve/muscle malfunction, were assessed in all individuals. At 30 days, 60 days, three months, six months, and a year, the participants' and investigators' Global Aesthetic Improvement Scales scores were compared [ 18 ]. Photographs were gathered to provide a thorough facial analysis. In addition, a self-assessment questionnaire was given to the patients. Blinded evaluators noted improvement in the midface and lower face in 93% of patients after six months. The satisfaction of the patients with results was 85%. After a year, the very same results were sustained. This study found that employing focused ultrasound, which delivers treatment at a single focal depth, significant outcomes in the overall aesthetic improvement of drooping of the mid and lower face can be accomplished.

Oni et al. conducted research on lower face laxity to find out the effectiveness and safety of novel micro-focused ultrasound (MFU) equipment [ 19 ]. The study included participants who had MFU treatment for skin tightening. The primary end measure was improvements in lower-face skin laxity, as measured by improvements in jawline abnormalities, submental laxity, and marionette line. Subject Global Aesthetic Improvement Scale (SGAIS) and Investigator Global Aesthetic Improvement Scale (IGAIS) evaluations were collected from two blinded dermatologists who paired before and after treatment images.

After one session of MFU administration, 24 individuals were examined after a median of 4.3 months. According to the IGAIS, five patients (20.9%) showed improvement while 15 subjects (62.5%) showed no particular change. Worsening was assigned to four individuals (16.7%). According to the SGAIS, 11 people (45.9%) claimed an improvement while nine people (37.5%) showed no specific change. Additionally, a statistically important difference was observed between the participant’s and investigators' improvement rates. Investigators had a lower score (P =.006). There were no major side effects [ 19 ]. The comparatively high improvement percentage reported in the subjects' self-assessments contrasted with the images' investigators' evaluations. It showed that novel evaluation methods, other than photography, are needed to reflect what subjects feel but clinical investigators cannot see.

There are some drawbacks to this study. First, due to the high expense of this cosmetic operation, only a restricted number of participants were involved in the study. Second, there was no control group in this study. Other limitations include that assigning subjective and objective assessments were built on pre and post-treatment images, which was not a quantifiable technique for assessment of rejuvenation of the skin.

Suh et al. revealed that 63.6% of patients had clinical improvement two months after using a new MFU device with multiple 440 lines for the submentum and cheeks. In the same investigation, more collagen fibers in the lower dermis, as well as between fat layers, were seen histopathologically. Suh and colleagues recently proposed an improved procedure for applying another MFU device that included 200 to 300 lines per face in each treatment session and a total of three sessions set apart four weeks. At the three-month follow-up, researchers found that skin laxity was substantially improved and was improved slightly in 32.1%, 57.1%, and 10.7% of all 28 individuals, respectively, compared to baseline, with no serious side effects such as facial fat atrophy [ 20 ].

In a different study by Chang et al., a total of 25 individuals were enrolled. The face and neck were irradiated with MFU-V utilizing two separate transducers: One of 4 MHz, 4.5-mm focal depth, and the other with 7 MHz, 3.0-mm focal depth, totaling 800 lines. At 0, 90, and 180 days, the participants were assessed using a skin complexion analysis as well as a 3-dimensional imaging system. The mean brow height lift and the submental lift were measured. All 25 subjects finished treatment and had their 90-day and 180-day follow-up exams. Two of the twenty-five participants were men [ 21 ]. The average age of the patients was 53.3 years (ranging from 39.8 to 61.1 years). Skin laxity was studied using three variables: texture, wrinkles, and pores. Only the decline in mean wrinkles scores after 90 days was statistically related and significant (p=0.0222). At 90 days, there was a 0.47 mm brow lift (p=0.0165), however, at 180 days, there was a 0.12 mm decrease in brow height as compared to baseline (p=0.6494). A mean submental lift of 26.44 mm was seen after 90 days (p=0.0217). At 180 days, there was a mean 13.76 mm submental lift (p=0.243).

Kerscher M et al. conducted a study to investigate the efficacy of micro-focused ultrasound in conjunction with imaging in clinical research and daily practice. According to guidelines, 22 women with moderate-to-severe skin sagging along the submental region and jawline received a single MFU-V therapy. Short-term effects were assessed for up to three days following treatment, whereas long-term effects were measured for up to 24 weeks post-treatment. Under standardized settings, transepidermal water loss, flexibility, erythema, skin hydration, temperature, density, and skin thickness were measured. A standardized numeric visual analog scale was used to assess pain.

The study found that after MFU-V therapy, skin temperature stayed within a physiologic range and that there was no marked increase on Day 3. Transepidermal water loss, erythema levels, and hydration remained very steady across time, with no significant variations between short- and long-term measures compared to baseline. Gross and net elasticity values were considerably lowered (with values of P=0.0001 and P=0.003, respectively) after the application of MFU-V therapy alone at Week 4, continued by considerably increased values at Week 12 (P=0.046 and P=0.015) and Week 24 (P=0.049 and P=0.001). The edema caused by MFU-V therapy went away without causing any complications. All of the patients' pain subsided quickly, following treatment. During the 24-week follow-up phase, no side effects were reported. MFU-V therapy is well-accepted in this trial, and it has no effect on the epidermal barrier function and on skin physiology [ 22 ].

In a study by Chen et al., participants got one to three full-face therapies by the focused ultrasound device. To produce a single pass of microthermal coagulation zones, three transducers were utilized without the application of contemporary anesthetics (7.0 MHz, 3.0 mm focal depth; 7.0 MHz, 4.5 mm focal depth; 4.0 MHz, 4.5 mm focal depth). Two independent physicians evaluated standardized pictures recorded at baseline and at each follow-up. About six months after treatment, negative effects were examined. Patient questionnaires were also used to examine subjective pain and tolerance scores. A total of 68 therapy sessions were completed by 49 Chinese patients having skin types III-IV, with a mean age of 53.3. Transcutaneous focused ultrasound seems to be safe for noninvasive skin tightening of the face in Asians, according to study findings. The side effects were minor and only lasted a short time. Up to six months after therapy, no major long-term or delayed side effects were seen [ 23 ].

Besides, the first evidence of clinical efficacy of micro-focused ultrasound therapy in non-facial areas was published by Alster and Tanzi. Two-fold plane therapy with the 4-MHz 4.5-mm-depth and 7-MHz 3-mm-depth transducers was compared to single therapy with the 4-MHz 4.5-mm-depth transducer alone. The study was performed on 18 women on areas of the knees, arms, or medial thighs. Two blinded physician evaluators determined the global evaluation scores of skin lifting and tightening, which were evaluated on a quartile grading scale. All three body sites showed statistically considerable improvement at six months of examination, with the knees and arms showing more visible improvement than the thighs. The dual-plane therapy also helped to smooth skin texture, which could be linked to more superficial dermal collagen remodeling. When asked how satisfied they were with the treatment's clinical efficacy, 13 of 16 patients said they were very satisfied [ 24 ].

Conclusions

MFU causes thermal tissue injury, resulting in microcoagulative zones that drive collagen neosynthesis and skin tightening. The lower face and neck, as well as non-facial areas, can yield promising outcomes. As a result, the use of MFU in cosmetic medicine is on the rise. Subsequently the effectiveness of MFU for facial rejuvenation, multiple independent scientists have successfully tested its application for tightening and lifting loose skin in various anatomic locations. Noninvasive skin raising of the upper arms, thighs, and knees is one of them. The efficacy of the MFU method is comparable to that of ablative or nonablative laser therapies, with minimal and temporary side effects. More research is required to govern the usage of MFU treatment for a larger range of clinical conditions.

The content published in Cureus is the result of clinical experience and/or research by independent individuals or organizations. Cureus is not responsible for the scientific accuracy or reliability of data or conclusions published herein. All content published within Cureus is intended only for educational, research and reference purposes. Additionally, articles published within Cureus should not be deemed a suitable substitute for the advice of a qualified health care professional. Do not disregard or avoid professional medical advice due to content published within Cureus.

The authors have declared that no competing interests exist.

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    Building research culture and capacity within the ultrasound department is a complex endeavour. It is important to acknowledge that despite some support from government and health organisations medical imaging departments exhibit low levels of research output. 7, 8 This can be due to several factors including organisational constraints and the ...

  19. The clinical ultrasound report: Guideline for sonographers

    Ongoing advances in ultrasound technology coupled with the wide availability of ultrasound and its excellent safety track record have resulted in increased clinical utility of ultrasound technology across all medical specialties and a dramatic rise in the clinical demand for ultrasound 1.

  20. Recent Advances in Artificial Intelligence-Assisted Ultrasound ...

    Ultrasound (US) is a flexible imaging modality used globally as a first-line medical exam procedure in many different clinical cases. It benefits from the continued evolution of ultrasonic technologies and a well-established US-based digital health system. Nevertheless, its diagnostic performance still presents challenges due to the inherent characteristics of US imaging, such as manual ...

  21. Transforming obstetric ultrasound into data science using eye ...

    Ultrasound is the primary modality for obstetric imaging and is highly sonographer dependent. ... In this paper, we demonstrate that ultrasound data science can offer fresh new clinical insights ...

  22. Scientist shows focused ultrasound can reach deep into the brain to

    The effect of focused ultrasound on those factors suggests a future direction for the Legon lab's research -- to explore the heart-brain axis, or how the heart and brain influence each other, and ...

  23. Review article: Use of ultrasound in the developing world

    There have been a multitude of small studies depicting novel uses of ultrasound in the developing world, but only a few studies have looked at the impact of ultrasound use on clinical management and patient outcomes, and whether ultrasound may be a sustainable modality for use in LMICs.

  24. A wearable ultrasound patch

    A wearable ultrasound patch. Ultrasounds can provide a wealth of information on organ function and disease; now scientists have engineered a stick-on wearable ultrasound device for continuous ...

  25. A Systematic Review of the Clinical Efficacy of Micro-Focused

    This literature study was intended to find the role and efficiency of using micro-focused ultrasound therapy in male and female patients aged 35-65. A total of 139 articles were extracted from the PubMed and Science Direct electronic databases.