Making Waves in Sonography Research | January 2022

JANUARY 2022

Making waves

IN SONOGRAPHY RESEARCH

Contents ABDOMINAL

Cystic artery velocity as a predictor of acute cholecystitis

3

WOMEN’S HEALTH

ISUOG practice guidelines (updated): use of Doppler velocimetry in obstetrics

5

WOMEN’S HEALTH

Giant breast masses: a pictorial essay

7

9 CARDIAC

Feasibility, reproducibility, and clinical implications of the novel fully automated assessment for global longitudinal strain

10

RESEARCH

How to read articles that use machine learning – users’ guides to the medical literature

12

VASCULAR

Pedal flow hemodynamics in patients with chronic limb – threatening ischemia

14

MUSCULOSKELETAL

Advanced ultrasound screening for temporomandibular joint (TMJ) internal derangement

16

MUSCULOSKELETAL

Ultrasound anatomy of the fingers: flexor

and extensor system with emphasis on variations and anatomical detail

19

© Australasian Sonographers Association 2022. Disclaimer : The information in this publication is current when published and is general in nature; it does not constitute professional advice. Any views expressed are those of the author and may not reflect ASA’s views. ASA does not endorse any product or service identified in this publication.

You use this information at your sole risk and ASA is not responsible for any errors or for any consequences arising from that use. Please visit www.sonographers.org for the full version of the Australasian Sonographers Association publication disclaimer.

Making waves

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ABDOMINAL REVIEWED BY Marilyn Zelesco ASA SIG Abdominal REFERENCE

Cystic artery velocity as a predictor of acute cholecystitis

Perez M, Tse JR, Bird K, Liang T, Brooken Jeffrey R, Kamaya A. Abdominal Radiology 2021; 44:4720 – 4728 READ THE FULL ARTICLE HERE

WHY THE STUDY WAS PERFORMED Acute right upper quadrant pain is a common complaint among patients presenting to the emergency department. Numerous clinical and societal guidelines recommend abdominal ultrasound as the first line imaging modality for patients with right upper quadrant pain and suspected biliary disease. Although ultrasound is over 96% accurate in the diagnosis of cholelithiasis, the sensitivity and specificity of ultrasound for acute cholecystitis is variable.

Gallbladder hyperemia has been observed in acute cholecystitis due to increased cystic artery flow. This article hypothesized that the cystic artery peak systolic flow (PSV) may be used as an ultrasound criterion to reflect acute inflammation and hence improve the accuracy of ultrasound in the diagnosis of acute cholecystitis.

HOW THE STUDY WAS PERFORMED The study was a retrospective analysis of 127 patients (> 18 years of age) who underwent an abdominal ultrasound with an indication specifically to investigate right upper quadrant pain.

The data was collected over an eight month period. The electronic medical record (EMR) was reviewed to identify patients who underwent definitive treatment within six days of the ultrasound examination (43 patients). Patients were excluded if they were pregnant, had a history of cirrhosis, hepatocellular cancer, TIPSS or hepatic metastases. To establish a control group, cystic artery PSV (angle corrected with an insonation angle of less than 60 degrees) was collected in 108 outpatients undergoing abdominal ultrasound. Patients with clinical suspicion of acute cholecystitis were excluded. In this control group, the cystic artery PSV was measurable in 30 out of 51 patients.

In summary, out of the 73 sampled cystic arteries: 22 had acute cholecystitis at surgery, 3 had acute cholecystitis based on cholecystostomy tube placement, 18 had chronic cholecystitis, and 30 compromised the control group.

Three radiologists independently assessed all the abdominal scan images and were blinded to the original report and pathological diagnosis. Each study was also evaluated for cholelithiasis, CBD diameter, stone impaction in the GB neck, sludge, GB wall thickness of > 3mm, GB distension of > 4cm in transverse and > 8 cm in length and tensile GB fundus sign (defined as the identification of a bulging gallbladder fundus against the anterior abdominal wall due to the resistance of being flattened by the anterior abdominal wall). Patient white cell count, patient heart rate, age and gender were also recorded.

WHAT THE STUDY FOUND Of 73 patients, 43 underwent definitive treatment: 40 patients underwent cholecystectomy and 3 had percutaneous cholecystostomy tube placement. Of the 43 patients, 25 had acute cholecystitis and 18 chronic cholecystitis. 30 control patients were examined.

There were no statistically significant differences between the 73 patients in terms of age, tachycardia, fever or mean white cell count.

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ABDOMINAL

Cystic artery velocity as a predictor of acute cholecystitis continued

Mean cystic artery PSV (CA PSV) was elevated in patients with acute cholecystitis, measuring 50 +/- 16 cm/s, versus 28 +/- 8 cm/s for chronic cholecystitis and 22 +/- 8 cm/s in the control group. There were no statistically significant differences between CA PSV in patients with chronic cholecystitis and the control group.

Mean hepatic artery PSV (HA PSV) was also elevated in patients with acute cholecystitis measuring 121 +/- 61cm/s, versus 86 +/- 45 cm/s in chronic cholecystitis and 71 +/- 24 cm/s in the control group. Similarly, there were no statistically significant differences between HA PSV in patients with chronic cholecystitis and the control group.

.... elevated cystic artery PSV (> 40 cm/s) was statistically correlated with acute cholecystitis.

In comparison of B-mode features of acute versus chronic cholecystitis, univariate analysis showed that GB wall thickness > 3mm, stone impaction and GB distension of > 8 cm were statistically significant. Other features such as CBD size, cholelithiasis, sludge, sonographic Murphy’s sign, transverse GB distensions > 4cm, pericholecystic fluid, tensile GB fundus sign and pericholecystic echogenic fat were not statistically significant.

RELEVANCE TO CLINICAL PRACTICE In an evaluation of patients with acute right upper quadrant pain, a cystic artery PSV of > 40 cm/s has a 72% sensitivity, 94% specificity, 95% PPV, 71% NPV and 81% accuracy for differentiating acute from chronic cholecystitis. n

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WOMEN’S HEALTH REVIEWED BY Sophie O’Brien ASA SIG Women’s Health REFERENCE

ISUOG practice guidelines (updated): use of Doppler velocimetry in obstetrics WHY THE STUDY WAS PERFORMED The study provides a practice guideline on the use of Doppler in ultrasound to assess the fetoplacental circulation of a pregnancy. The study aims to guide the ultrasound user on pulsed Doppler ultrasound and its different applications including spectral, colour flow, and power Doppler. The use of the techniques of Doppler ultrasound defined in the study aims to increase reproducibility and minimize technical errors that arise throughout the scan. The guideline also recognises the significance of not exposing the fetus unnecessarily or for a prolonged period, particularly in the 1st trimester.

Bhide A, Acharya G, Baschat A, Bilardo CM, Brezinka C, Cafici D, Ebbing C, Hernandez-Andrade E, Kalache K, Kingdom J, Kiserud T, Kumar S, Lee W, Lees C, Leung KY, Malinger G, Mari G, Prefumo F, Sepulveda W, Trudinger B. ISUOG Practice Guidelines (updated): use of Doppler velocimetry in obstetrics. Ultrasound Obstet Gynecol 2021; 58: 331–339.

READ THE FULL ARTICLE HERE

HOW THE STUDY WAS PERFORMED The authors describe commonly used techniques and principles of Doppler ultrasound in obstetric imaging acknowledging solid scientific literature. The authors provided the grade of recommendation used in the guideline to ensure strong scientific evidence was used.

WHAT THE STUDY FOUND When assessing a pregnancy using Doppler ultrasound the ultrasound machine must be able to perform colour Doppler and spectral wave analysis as well as calculate the maximum velocity. In addition to this, the machine should be able to calculate the peak systolic velocity (PSV), the end diastolic velocity (EDV), time average maximum velocity, the resistive index (RI) and pulsatility index (PI) of a vessel.

Samples of vessels should be acquired whilst the fetus is still and not breathing. Colour mapping can assist the user in identifying vessels and guide where to position the sample, however not required. Ideally the angle of insonation should be as close to zero as possible without angle correction. The greater the angle of insonation, the greater the error in velocity.

Doppler settings should be adjusted for optimization. This includes the wall filter (50-60MHz), PRF (low enough to enable visualization of the vessel) and appropriate sweep speed. Multiple samples should be obtained to prove reproducibility but not averaged.

Uterine artery Doppler waveforms are obtained transabdominally by showing the mid sagittal plane of the uterus with the cervix in view and moving laterally till the uterine arteries are seen at the paracervical plexus. The uterine artery should be seen ascending cranially as it goes into the uterine body. Measurements should be taken prior to the main uterine artery branching into arcuate arteries, where the PSC is >60cm/sec.

There is great variance of Doppler flows amongst the umbilical artery between the fetus and the placenta with the velocity at its highest at the fetal end of the umbilical cord.

Measurements and samples of the umbilical artery should be obtained in a free loop to ensure consistency. Multiple measurements can also be taken at different locations along the cord to show reproducibility and consistency.

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WOMEN’S HEALTH

ISUOG practice guidelines (updated): use of Doppler velocimetry in obstetrics continued

The Middle Cerebral Artery (MCA) is visualised in a transverse plane of the mid brain caudal to the transthalmic plane as it arises from the Circle of Willis. Sampling of the MCA should take place in the proximal 3rd of the vessel close to its origin. Between 3 and 10 consecutive waveforms is recommended. Whilst measuring PSV with a manual trace is acceptable, autotrace is preferred when calculating the PI and RI. Ductus venosus (DV) is seen by connecting the umbilical vein to the IVC in the abdomen using either a transverse or a longitudinal plane however, sampling is best in the mid sagittal plane. Colour mapping of the DV demonstrates a high velocity vessel. The waveform varies, usually triphasic, although biphasic waveforms have been seen in healthy fetuses.

Multiple samples should be obtained to prove reproducibility, but not averaged.

RELEVANCE TO CLINICAL PRACTICE Doppler is an integral part of assessing a fetus and is a technical aspect of our role as a sonographer. Up to date guidelines provide sonographers with the tools to accurately assess the fetus and ensure the wellbeing of a pregnancy. n

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WOMEN’S HEALTH REVIEWED BY Gina Humphries ASA SIG Women’s Health REFERENCE

Giant breast masses: a pictorial essay

Chitty C, Dessauvagie B, Taylor D. Giant breast masses: a pictorial essay. J Med Imaging Radiat Oncol. 2019;63:467–72 READ THE FULL ARTICLE HERE

WHY THE STUDY WAS PERFORMED: This pictorial essay discusses the imaging and pathological findings of a range of giant breast lesions. Some lesions demonstrate characteristic mammographic appearances. These include lipomas and hamartomas. Other lesions may be mammographically indistinguishable, such as simple cysts and some malignant breast carcinomas. Ultrasound may help further characterisation through the demonstration of a range of ultrasound specific characteristics such as posterior enhancement, internal septation and increased vascularity. This information increases the likelihood of diagnostic accuracy and may guide clinical management.

WHAT THE PAPER COVERS: The paper reviewed the pathophysiology and epidemiology as well as the mammographic and ultrasound appearances of giant fibroadenomas, phyllodes tumours, lipomas, hamartomas, cystic lesions, breast abscesses, breast hamartomas and breast carcinomas.

Giant fibroadenomas are common benign masses that are classified as ‘giant’ at diameters >5-10cm. They appear as well-circumscribed masses with similar echogenicity to the surrounding breast tissue on a mammogram. Under ultrasound, fibroadenomas are homogenous rounded masses, hypo- to iso-echoic and often demonstrate vascularity.

Phyllodes tumours are rare lesions that appear similar to fibroadenomas on mammogram.

Ultrasound may present with a variety of appearances making further imaging or histopathological investigation necessary in the diagnosis of a phyllodes tumour.

Lipomas are benign encapsulated lesions that may not be well seen on mammogram.

Sonographically, they are well-circumscribed lesions with no posterior enhancement, minimal or no vascularity and may demonstrate variable echogenicity.

Hamartomas demonstrate a characteristic well-circumscribed encapsulated lesion on mammogram. Conversely, the ultrasound appearance is variable limiting its use as a diagnostic tool.

Cystic lesions may be simple, complicated or complex and so present with a variety of appearances. On mammogram, cysts are round, well-defined lesions. Ultrasound appearance may vary from anechoic and well-defined with posterior acoustic enhancement to a mass with solid components, septations, thick walls, vascularity, debris and/or a lack of posterior acoustic enhancement.

Breast abscess is often a complication of mastitis. Ultrasound may demonstrate size, depth and number of septations. Mammogram may be used as a tool to demonstrate malignancy in atypical presentations and also to monitor resolution.

Breast haematomas often occur in the setting of trauma. Mammogram demonstrates asymmetrical densities or well-circumscribed dense nodules with associated peripheral oedema. The appearance of a haematoma changes under ultrasound with age of the lesions from hyperechoic in the early stages to hypoechoic in later stages.

Breast carcinoma is seen as a soft tissue mass on mammogram that may include spiculation

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WOMEN’S HEALTH

Giant breast masses: a pictorial essay continued

and microcalcifications. Under ultrasound, breast carcinoma may show an irregular, ill-defined and hypoechoic mass. Spiculations, calcification and posterior acoustic shadowing may also be seen.

HOW THE PAPER WAS WRITTEN: A comprehensive review of giant breast masses was performed by Chitty, Dessauvagie and Taylor.

RELEVANCE TO CLINICAL PRACTICE:

… lesions may be mammographically indistinguishable and ultrasound (US) may be helpful in further characterisation.

Providing concise but comprehensive information on the mammographic appearance and ultrasound appearance of a range of giant breast masses may allow the sonographer to confidently apply this information in a clinical setting. This may further diagnostic assessment and understanding of lesions encountered in daily practice. Providing appropriate imaging to the clinician can help differentiate benign from malignant breast lesions which in turn may guide appropriate management of the patient. n

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PAEDIATRIC REVIEWED BY Cain Brockley ASA SIG Paediatric REFERENCE

Pediatric living donor left lateral segment liver transplantation biliary atresia: Doppler ultrasound findings in early postoperative period

Tang, Y. Zhang, G. Kong, W., et al.

Japanese Journal of Radiology READ THE FULL ARTICLE HERE

WHY THE STUDY WAS PERFORMED: To determine normal changes of hepatic hemodynamic measurements in the immediate period following transplant of a left lobe cutdown in paediatric patients. To use that data to create valuable reference values for sonographers, radiologists, and treating clinicians that will assist in better identifying early postoperative vascular complications versus normal post operative changes.

HOW THE STUDY WAS PERFORMED: The study was a retrospective analysis of 227 biliary atresia patients who had undergone left segment liver transplant, with a total of 1135 Doppler examinations performed in the first week post-transplant.

The examinations were reviewed and the hemodynamic measurements including peak systolic velocity (PSV), end diastolic velocity (EDV), resistive index (RI) and pulsation index (PI) of the hepatic artery, the portal vein velocity and flow, and the hepatic vein velocities were documented.

This information was collected from the intra-operative scan, and those examinations performed on the first, third, fifth, and seventh-day post operation. The examinations were performed by experienced staff.

The liver function tests were also collected for each day for correlation. The data was then analysed to determine trends over the week period. The patients included all recovered normally after transplant with normal function achieved.

“Understanding normal flow dynamic changes in the immediate post-transplant period assists in separating vascular complications from normal expected changes.”

WHAT THE STUDY FOUND: The study found that the biochemical liver function markers improved over the week posttransplant, as the patient recovered. The Doppler parameters and measurements demonstrated a consistent change during the post operative period assessed, especially the Hepatic artery (HA). The HA PSV & EDV demonstrated a decrease over the first few scans to day 3, with a consequent rise on the day 5 and 7 examinations. Conversely the hepatic artery PI & RI demonstrated the opposite trend with a rise in value to day 3, followed by a decrease on day 5 and 7. The portal vein measurements, velocity and flow were found to vary widely, however a reference range for each day was established.

Doppler ultrasound was able to quantitively monitor the changes in hepatic hemodynamic parameters and normal reference values were able to be established. The authors conclude that the results obtained suggest that patients with measurement values below the reference values during the immediate post operative period may need to be monitored more closely.

RELEVANCE TO CLINICAL PRACTICE: Though performed at a single centre, this article is a good beginning to better understanding the flow changes in left lobe cut-down transplants in the first week post-operation. During the first week post-transplant there is a higher risk of vascular complications for these patients and by understanding normal changes it is easier to identify actual complications. This article will be especially relevant to paediatric sonographers who perform these studies, and to help those who are less experienced to understand the normal hemodynamic changes expected post-transplant. n

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CARDIAC REVIEWED BY Chrissy Thomson ASA SIG: Cardiac REFERENCE

Feasibility, reproducibility, and clinical implications of the novel fully automated assessment for global longitudinal strain

Kawakami H, Wright L, Nolan M, Potter E, Yang H, Marwick T. J Am Soc Echocardiogr 2021; 34:136-45 READ THE FULL ARTICLE HERE

WHY THE STUDY WAS PERFORMED: The aim of this study was to compare the feasibility, reproducibility and predictive value of fully automated global longitudinal strain (GLS) analysis with manual and semiautomated assessment of GLS.

HOW THE STUDY WAS PERFORMED: In this retrospective study, GLS analysis was performed on echocardiograms from 561 asymptomatic patients (≥65 years) with heart failure risk factors. All patients were required to have image quality sufficient for GLS analysis and available data on follow-up outcomes of cardiac events (new heart failure and cardiac death). Left ventricular GLS was performed on apical 4, apical 2 and apical long-axis images and was calculated using three methods – fully automated, semi-automated (whereby the automated analysis was adjusted by an experienced investigator) and manual analysis. In addition, a subset of 50 randomly selected patients was evaluated for calculation time, and inter- and intra-observer variability.

WHAT THE STUDY FOUND: The fully automated GLS analysis was reviewed by an experienced investigator and found to be feasible in 60.6% of patients. Of note, the apical segments in all views, the mid anterior and the basal anteroseptum required frequent manual correction (40% of cases). Figure 1 demonstrates the quality of automated tracking in each segment.

Figure 1 – adapted from Figure 2: J Am Soc Echocardiogr 2021;34:136-45

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CARDIAC

Feasibility, reproducibility, and clinical implications of the novel fully automated assessment for global longitudinal strain The mean value of fully automated GLS (absolute values) was 17.6 ± 3.1% compared with 19.4 ± 2.3% for semi-automated and 18.5% ± 2.6% for manual GLS. Using cut-off values of ≥18% (normal), >16-<18% (borderline) and <16% (abnormal), a considerable number of patients who were classified as borderline or abnormal using fully automated GLS were reclassified as normal when using semi-automated or manual GLS. Whilst the data demonstrated that fully automated GLS was found to be effective for the detection of normal and abnormal LV function, it was significantly less effective than semiautomated analysis. In addition, semi-automated GLS was found to be most effective at predicting cardiac events in the cohort.

As would be expected, the calculation time for fully automated GLS (0.5 ± 0.1min/patient) was significantly shorter than for semi-automated (2.7 ± 0.6min/patient) and manual assessment (4.5 ± 1.6min/patient). Automated GLS also demonstrated the highest degree of reproducibility compared with the other methods.

...the semiautomated approach seems to provide a better balance between feasibility and clinical relevance at this stage.

RELEVANCE TO CLINICAL PRACTICE: GLS is increasingly being incorporated into clinical decision making and its use is supported by many guideline documents. The ability to produce accurate, reproducible data is essential. Whilst automated GLS is extremely fast to perform, is feasible and has excellent reproducibility, manual adjustment is still required in a substantial number of cases to improve accuracy. This suggests, at this stage, that fully automated GLS should not be solely relied upon and careful analysis and adjustment of GLS tracking is often required by an experienced operator.

Previous research by Chan et al1 suggests that ‘expert competency’ in performing strain analysis can be achieved in as little as fifty cases across a three month period. Whilst a learning curve does exist, it is not an onerous one, with clear benefits in relation to accuracy and predictive value compared to fully automated analysis. n

REFERENCES 1 Chan J, Shiino K, Obonyo N, Hanna J, Chamberlain R, Small A, et al. Left ventricular global strain analysis by twodimensional speckle-tracking echocardiography: the learning curve. J Am Soc Echocardiogr 2017;30:1081-90

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RESEARCH REVIEWED BY Caterina Watson ASA SIG Research REFERENCE

How to read articles that use machine learning – users’ guides to the medical literature

Liu,Y., Cameron, P., Krause, J., Peng, L. The Journal of the American Medical Association READ THE FULL ARTICLE HERE

WHY THE STUDY WAS PERFORMED: This paper is an introductory synopsis for readers of any machine learning article from medical imaging or computer vision journals. The user guide describes 3 goals to promote understanding of machine learning models with a critical eye: 1. To emphasise the importance of model validation.

2. Review basics of machine learning.

3. Review model implementation into clinical practice.

The building blocks of machine learning are explained, with differences defined between machine learning vs deep learning, and supervised vs unsupervised learning methods.

Essential technical language is made accessible from quality glossary lists. These grounding terms have been cited in many subsequent articles, and form a useful repository for students of machine learning. While it may require more than one read to absorb the major and minor points, the emphasis throughout the article relates to how best apply machine learning research for the benefit of clinical practice. Clinical intuition and standard statistical principles still apply when it comes to evaluating machine learning/mathematical models.

HOW THE STUDY WAS PERFORMED: The reader is stepped through a clinical research scenario for annual diabetic retinopathy screening. A hypothetical literature search produces articles which are difficult to compare, as each paper uses different data sets – test sensitivity vs independent samples vs clinical setting. This is familiar territory, and easily translates to appreciate the problems encountered for deriving, validating and establishing the clinical effectiveness of a machine learning tool.

WHAT DOES THE STUDY PROVIDE? The following question list and dictionaries can be used to help understand and evaluate a machine learning study. For brevity, dictionary terms are simply listed.

1) Questions to assess the Validation of Machine Learning Models: • Is the reference standard high quality? i) Expert panel will reduce human judgement errors (interrater variability). ii) Experts blinded to machine learning predictions reduce bias.

• Is the study design appropriate? i) Did the patient sample include an appropriate spectrum of patients to reflect a similar cohort in clinical practice? ii) A high quality design will ensure the validation data set is isolated from the training and tuning tasks.

• Are the results unexpected? i) For machine learning studies, results can only be as good as the training data

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RESEARCH

How to read articles that use machine learning – users’ guides to the medical literature continued supplied. Test results should not exceed expert annotation. ii) Unexpected claims have arisen from retinal screening images and race/sex assignment. Independent researchers need to validate these findings with external cohorts. The results may be due to artifacts in the machine learning system, confounding factors, or flaws in the study design.

2) Glossary of general terminology associated with machine learning methods: Feature; Hyperparameter; Label; Machine Learning; Artificial Intelligence; Deep Learning; Model; Algorithm; Overfitting; Parameter; Reference standard; Training; Tuning.

3) Glossary of terms associated with machine learning methods: Types of machine learning schemes; Data set names [ Development set; K-fold cross validation; Training set; Tuning set; validation set ]; Regularisation [ Data augmentation; Early stopping; Ensemble; Fine tuning/Pre-initialisation/Warm start; Parameter regularisation].

Machine learning is a tool to clarify the relationship between data and clinical features... clinical intuition and standard statistical principles still apply.

RELEVANCE TO CLINICAL PRACTICE: Machine learning is a tool to clarify the relationship between data and clinical features.

Sonographers should identify overly optimistic model performance in research reports.

A large gap in performance between tuning and validation may indicate overfitting to the tuning set. Clinical factors may also contribute to performance, such as population age or disease subtype. Assessment of overfitting involves machine learning expertise (qualitative assessment of tuning-validation performance gap) and clinical intuition (qualitative assessment of patient population differences between development and validation sets). It remains critical to know if performance remains high with external cohorts. n

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VASCULAR REVIEWED BY Daniel Rae ASA SIG Vascular REFERENCE

Pedal flow hemodynamics in patients with chronic limb – threatening ischemia

J. Sommerset, D. Teso, R. Karmy-Jones, Y. Vea and B. Feliciano. Journal of Vascular Ultrasound READ THE FULL ARTICLE HERE

WHY THE STUDY WAS PERFORMED: Whilst it is standard practice to image the three-vessel run-off at the ankle, sonographers tend to stop scanning at the ankle. There is also have a poor understanding of pedal arterial anatomy and how it collateralises when disease is present. With the advances in ultrasound technology, it is now possible to comprehensively evaluate the haemodynamic flow in the pedal arterial system. This is important as it gives an understanding of the perfusion in this region, which will help with the prediction of wound healing in the foot and can aid in interventional planning.

HOW THE STUDY WAS PERFORMED: The paper begins by going over the arterial anatomy at the foot on both the dorsal and the plantar aspect and how these vessels branch to perfuse the toes. This is demonstrated in diagram 1 below.

It also covers important collateral pathways from the peroneal artery at the ankle; • Posterior Communicating Artery (PCA) and the Lateral Calcaneal Branch (LCB) both communicate from the Peroneal Artery to the Posterior Tibial Artery • The Anterior Communicating Artery (ACA) communicates from the Peroneal Artery to the Anterior Tibial Artery (ATA) The paper goes on to describe a 12 month retrospective review that was performed on thirty patients with peripheral vascular disease. This was to evaluate the changes in haemodynamic flow in the foot with ultrasound when different areas of occlusion were present.

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VASCULAR

Pedal flow hemodynamics in patients with chronic limb – threatening ischemia

WHAT THE STUDY FOUND: When retrograde flow is identified in the arcuate artery, one should be suspicious of more proximal obstruction in the anterior circulation (ATA) When retrograde flow is identified in the lateral and/or deep plantar, one should be suspicious of proximal obstruction in the posterior circulation (PTA) This has been well demonstrated in diagram 2.

Duplex imaging has improved our understanding of the arteries in the foot tremendously.

RELEVANCE TO CLINICAL PRACTICE: Improved sonographer understanding of the arterial system in the foot and how the haemodynamics change with disease will aid vascular surgeons in the management and interventional planning for patients with chronic limb-threatening ischemia. As ultrasound techniques for evaluating disease in the foot develop further, understanding these haemodynamics will become essential. n

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MUSCULOSKELETAL REVIEWED BY Michelle Fenech ASA SIG Musculoskeletal REFERENCE

Advanced ultrasound screening for temporomandibular joint (TMJ) internal derangement

Friedman SN, Grushka M, Beituni HK, Rehman M, Bressler HB, Friedman L. Advanced Ultrasound Screening for Temporomandibular Joint (TMJ) Internal Derangement. Radiol Res Pract. 2020; 2020:1809690.

READ THE FULL ARTICLE HERE

WHY WAS THE STUDY PERFORMED? The temporomandibular joint (TMJ) exists between the mandibular condyle and the concave mandibular fossa (or glenoid fossa) of the temporal bone, and the convex articular eminence of the temporal bone (Figure 1). This joint is unique in that all the articular surfaces are covered by fibrocartilage instead of articular cartilage1. The TMJ contains a flexible fibrocartilage disc which is reported to be 2mm thick anteriorly and 3 mm thick posteriorly2. This hinge joint allows both forward and backward translation of the mandibular condyle and articular disc2. Internal derangement of the TMJ is defined as a mechanical fault of the joint that interferes with smooth joint function which is attributed to abnormal interaction between the articular disc, condyle and articular eminence1. Articular disc displacement is the most common cause of internal derangement of the TMJ3. Disc displacement is categorised based on the relationship of the disc to the mandibular condyle and can be described as anterior, anterolateral, anteromedial, lateral, medial and posterior1. The most common pattern of disc displacement is either anterior or anterolateral, which accounts for more than 80% of disc displacement4.

Figure 1. Anatomy of the Temporomandibular joint (TMJ) with the mouth in the closed position. MC = mandibular condyle, AE = articular eminence of temporal bone, MF = mandibular fossa of temporal bone, EAM = external auditory meatus.

Fibrocartilage lining MF, AE and MC shown in blue.

Articular disc displacement is the most common cause of internal derangement of the TMJ

Sonographic assessment of the TMJ may be undertaken to investigate the structural integrity of the TMJ using static and dynamic imaging and identify structural changes such as displacement or snapping of the articular disc if present and guide injections if required3,5.

Such a request can induce panic in a sonographer, particularly if they are not familiar with the relational anatomy, sonographic technique, and normal and abnormal sonographic appearances of this joint. This study was undertaken to investigate a sonographic technique that may be used for dynamic and static imaging of the TMJ and as a screening diagnostic tool for TMJ internal derangement6.

HOW WAS THE STUDY PERFORMED? Sonographic imaging of the TMJ using a defined technique was compared with coronal and sagittal magnetic resonance (MR) imaging in bilateral TMJs in 10 asymptomatic control participants (between 20 and 30 years of age). The main structures identified include the mandibular condyle, mandibular fossa, articular eminence, and articular disc.

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MUSCULOSKELETAL

Advanced ultrasound screening for temporomandibular joint (TMJ) internal derangement continued A 15-7 MHz hockey stick transducer (L15-7io, Philips iU22 Ultrasound System, Netherlands) was used to obtain sonographic imaging of the long axis of the articular disc. To do this, the transducer was placed parallel to the articular disc when the mouth was in three positions and the transducer orientation was described in terms of a clock face: 1. In closed mouth position – transducer oriented in either 5 o’clock (right TMJ) or 7 o’clock (left TMJ) position 2. In semi-open mouth position – transducer oriented in either 3 o’clock (right TMJ) or 9 o’clock (left TMJ) position 3. In open mouth position – transducer oriented in either 1 o’clock (right TMJ) or 11 o’clock (left TMJ) position (Figure 2).

Sonographic and MR imaging of 61 symptomatic participants was also conducted (using same sonographic technique described above) to compare imaging findings.

WHAT THE STUDY FOUND

Figure 2. Transducer positions (outlined by black rectangle) to demonstrate the long axis of the articular disc with the mouth in 3 positions: A. Closed mouth B. Semi-open mouth C. Open mouth

In the control population, the normal articular disc appeared as a bowtie or saddle shape on MR imaging. Sonographically, the disc appears as a hypoechoic c-shaped structure that straddles the hyperechoic mandibular condyle. During dynamic mouth opening, the normal articular disc maintains a constant relationship and rainbow shape between the mandibular condyle and temporal bone as the mandibular condyle moves anteriorly (Figure 3).

In the case population disc displacement was defined in this study and was classified as:

Figure 3. Shape and position of the normal articular disc which can be identified sonographically in the closed (A) and open mouth (B) positions. AE = Articular eminence of temporal bone, MF = mandibular fossa of temporal bone, MC = mandibular condyle. Articular disc = blue semicircular structure which moves in relation to the mandibular condyle.

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MUSCULOSKELETAL

Advanced ultrasound screening for temporomandibular joint (TMJ) internal derangement continued anterior, posterior, medial and lateral displacement relative to the mandibular condyle1. Medial and lateral displacement of the articular disc was not able to be identified confidently using sonographic imaging in this study. Displacement of the articular disc may be sub-classified as anterior displacement with reduction (anteriorly displaced disc returns to normal position on mouth opening), and anterior displacement with no reduction (anteriorly displaced disc does not return to a normal position with mouth opening which can result in a locked jaw)1. This classification was used in this study. Disc displacement can be further described as either be complete or partial, however these descriptions were not used to define displacement in this study. Furthermore, deformation of the shape of the disc and/or irregularity of the bony contour of mandibular condyle may be identified sonographically but also was not noted in this study.

29 of the 61 case participants had disc pathology identified on MR imaging. Sonographic imaging demonstrated disc pathology in 23 participants (79% sensitivity, 100% specificity when compared to MR imaging). Anterior displacement was the most common type of disc displacement identified.

RELEVANCE TO CLINICAL PRACTICE A sonographic assessment of the TMJ may be requested, and an understanding of the structures to be imaged, the sonographic technique, the normal and abnormal sonographic appearances, particularly the position of the articular disc in reference to the mandibular condyle, and an understanding of pathology encountered is required and is outlined nicely in this paper. n

REFERENCES 1. Bag AK, Gaddikeri S, Singhal A, Hardin S, Tran BD, Medina JA, et al. Imaging of the temporomandibular joint: An update. World J Radiol. 2014;6(8):567-82.

2. Alomar XM, Medrano JM, Cabratosa JM, Clavero JAM, Lorente MM, Serra IM, et al. Anatomy of the Temporomandibular Joint. Semin Ultrasound CT MR. 2007;28(3):170-83.

3. Tu K-H, Chuang H-J, Lai L-A, Hsiao M-Y. Ultrasound Imaging for Temporomandibular Joint Disc Anterior Displacement. J Med Ultrasound. 2018;26(2):109-10.

4. Paesani D, Westesson PL, Hatala M, Tallents RH, Kurita K. Prevalence of temporomandibular joint internal derangement in patients with craniomandibular disorders. Am J Orthod Dentofacial Orthop. 1992;101(1):41-7.

5. Klatkiewicz T, Gawriołek K, Pobudek Radzikowska M, Czajka-Jakubowska A. Ultrasonography in the Diagnosis of Temporomandibular Disorders: A Meta-Analysis. Medical science monitor : international medical journal of experimental and clinical research. 2018;24:812-7.

6. Friedman SN, Grushka M, Beituni HK, Rehman M, Bressler HB, Friedman L. Advanced Ultrasound Screening for Temporomandibular Joint (TMJ) Internal Derangement. Radiol Res Pract. 2020;2020:1809690.

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JANUARY 2022 | 18

MUSCULOSKELETAL REVIEWED BY Sophie O’Brien ASA SIG Musculoskeletal REFERENCE

Ultrasound anatomy of the fingers: flexor and extensor system with emphasis on variations and anatomical detail

De Maeseneer M, Meng J, Marcelis S, Jager T, Provyn S, Shahabpour M. J Ultrason. 2020 Jul; 20(81): e122–e128.

READ THE FULL ARTICLE HERE

WHY THE STUDY WAS PERFORMED: The finger is a small and complex part of our anatomy. Alongside complex anatomy, variants exist within both the flexor and extensor tendons of the finger. Being aware of these variations can prevent misdiagnosis when assessing the finger anatomy with ultrasound.

HOW THE STUDY WAS PERFORMED: The study was performed by using high frequency ultrasound and a dedicated MSK ultrasound system on both volunteers and patients to obtain images of the anatomy of the finger. They then obtained images of the finger of fresh cadaver specimens with ethics board approval. Both ultrasound images and cadaver specimen images were then used to demonstrate clinically relevant anatomy of the finger including complex structures and anatomical variations.

WHAT THE STUDY FOUND: Accurate knowledge of the complex anatomy of the finger avoids misdiagnosis of pathology.

By using images from cadaver specimens and directly correlating them with the ultrasound appearance of these structures the authors are able to show the variance in anatomy accurately.

The anatomy of the extensor tendons is small and complex and varies between the 2nd and 3rd, 4th fingers. The extensor tendons of the 3rd and 4th fingers are broad with multiple tendon fibres that can be mistaken for pathology. 2 tendons are often seen at the 2nd finger, one of which, the extensor indicis proper used as a graft. The 5th finger has a minimum of 2 extensor tendons.

Ultrasound examination of the central slip and distal tendon allows for dynamic assessment of the anatomy.

... being aware of these variations can prevent misdiagnosis

The sagittal bands are an important structure preventing subluxation of the extensor tendons.

Where there are multiple tendons present, injury to the sagittal bands can also impact the connection between the multiple tendons.

Along the course of the finger, the relationship between the flexor digitorum profundus (FDP) and the flexor digitorum superficialis (FDS) varies. The FDS bifurcates and inserts laterally onto the middle phalanx, whilst the FDP inserts onto the distal phalanx. The FDP can show a continuous bifurcation in the tendon ill its insertion which is a normal variation and not a tear of the tendon.

The pulley system is integral in keeping the flexor tendons adjacent to the bones. Whilst normally the A1, A2, and A3 pulley are separate structures, they can be fused. The A1 pulley can also extend down into the hand proximally. This can be called the A0 pulley and is important to be noted when assessing the finger for trigger finger.

RELEVANCE TO CLINICAL PRACTICE: The study provides detailed analysis of the anatomy of the finger and its anatomical variations.

As sonographers we need to be aware of these variants so we can precisely assess the anatomy and pathology. This allows for an accurate diagnosis. n

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JANUARY 2022 | 19