Imaging of Peripheral Nerves: AJR Expert Panel Narrative Review.

Peripheral nerve imaging provides information that can be critical to the diagnosis, staging, and management of peripheral neuropathies. MRI and ultrasound are the imaging modalities of choice for clinical evaluation of the peripheral nerves given their high soft tissue contrast and high resolution, respectively. This AJR Expert Panel Narrative Review describes MRI- and ultrasound-based techniques for peripheral nerve imaging; highlights considerations for imaging in the settings of trauma, entrapment syndromes, diffuse inflammatory neuropathies, and tumor; and discusses image-guided nerve interventions, focusing on nerve blocks and ablation.

Preoperative Ultrasound-Guided Localization of the Lateral Femoral Cutaneous Nerve: From Guide Wire to Novel Clip.

BACKGROUND AND OBJECTIVE: Lateral femoral cutaneous nerve (LFCN) decompression and transposition are surgical treatment options for meralgia paresthetica. Identifying the LFCN during surgery may be challenging, and preoperative localization is a valuable adjunct in this case. The objective of this study was to explore a new technique using preoperative ultrasound-guided clip localization (USCL) of the LFCN. METHODS: After Institutional Review Board approval, data were collected on patients who underwent both preoperative ultrasound-guided wire localization (USWL) and USCL over the past 13 years. Skin-to-nerve time was calculated prospectively. RESULTS: Fifty-six patients were identified, 51 had USWL and 5 had USCL; the skin-to-nerve median time was 7.5 and 6 minutes, respectively. Six wires were misplaced, and this was at the beginning of utilization of the USWL technique. There were no nerve injury, infection, or bleeding complications related to either wire or clip placement. CONCLUSION: USWL or USCL is safe and time-efficient in LFCN surgeries.

Ultrasound-guided nerve block prior to biopsy of suspected neurogenic tumors: safety and feasibility in a pilot study.

OBJECTIVE: The aim of this study is to investigate the safety and feasibility of ultrasound-guided nerve block prior to biopsy of potentially neurogenic tumors. MATERIALS AND METHODS: A retrospective review of the medical record from June 2017 to June 2022 identified ultrasound-guided biopsies of potentially neurogenic tumors that were performed with a pre-procedural nerve block. Patient demographics, biopsy site, number of passes, needle gauge, use of sedation, pathology results, and procedural complications were recorded and summarized. RESULTS: The structured search found 16 patients that underwent biopsies of 18 potentially neurogenic tumors with the use of a pre-procedural nerve block at a variety of upper and lower extremity locations. Average patient age was 52 (range 18-78) and 9 patients (56%) were female. Of the 16 patients, 10 were performed without intravenous sedation. Three patients were unable to tolerate biopsy until a nerve block was used. All biopsies yielded a diagnostic sample with 13 of the tumors neurogenic in origin. One patient reported mild postprocedural pain which resolved with conservative treatment; no other complications were reported. CONCLUSION: Nerve block prior to ultrasound-guided biopsy of potentially neurogenic tumors is a safe and feasible technique. Further study is needed to determine the extent to which nerve block can decrease intra-procedural pain and reduce or eliminate the need for sedation during biopsy.

Shear wave elastography imaging in a porcine tendinopathy model.

OBJECTIVE: To quantify the effect of structural damage in an ex vivo animal tendinopathy model using shear wave elastography (SWE). MATERIALS AND METHODS: Sixteen porcine flexor tendons were injected with a 0.05 mL bolus of 1.5% collagenase solution to induce focal structural damage without surfacing tears. Control tendons were injected with saline (n = 16). Eight tendons from each group were incubated at 37 °C for 3.5 h while the remaining 8 from each group were incubated for 7 h. Tendons were mechanically stretched to 0% and 1% strain. Simultaneously, SWE was acquired proximal to, at, and distal to the injection site using a clinical ultrasound scanner. RESULTS: There were significant differences in SWS (saline > collagenase) at 1% strain and 7-h incubation for all three locations (PROX p = 0.0031, ROI p = 0.001, DIST p = 0.0043). There were also significant differences at 0% strain and 7 h, but only at (p = 0.0005), and distal to (p = 0.0035), the injection site. No statistically significant differences were observed for 3.5-h incubation, at 0% or 1% strain. CONCLUSIONS: Collagenase-mediated structural damage does appear to convey decreased tissue elasticity on SWE when ex vivo tendons are incubated for 7 h. These findings suggest that SWE may be a useful tool for predicting ultimate tissue strength in tendinopathic tissues. Pull-to-failure testing should be performed in the future and are expected to show that tendons with decreased SWS, and, therefore, decreased elasticity, rupture at lower pulls forces.

Ultrasonography of Superficial Soft-Tissue Masses: Society of Radiologists in Ultrasound Consensus Conference Statement.

The Society of Radiologists in Ultrasound convened a panel of specialists from radiology, orthopedic surgery, and pathology to arrive at a consensus regarding the management of superficial soft-tissue masses imaged with US. The recommendations in this statement are based on analysis of current literature and common practice strategies. This statement reviews and illustrates the US features of common superficial soft-tissue lesions that may manifest as a soft-tissue mass and suggests guidelines for subsequent management.

Contrast-enhanced ultrasound-guided musculoskeletal biopsies: our experience and technique.

OBJECTIVE: To present our experience with contrast-enhanced ultrasound (CEUS)-guided musculoskeletal soft tissue biopsies in a busy interventional clinic. MATERIALS AND METHODS: After IRB approval was obtained and informed consent was waived, we retrospectively reviewed all CEUS-guided musculoskeletal biopsies performed from December 1, 2018 to March 2, 2020. Relevant pre-procedure imaging was reviewed. Number of samples, suspected necrosis on pre-procedure imaging, specimen adequacy for pathologic analysis, correlation with pathologic diagnosis of surgical resection specimens, and procedural complications were recorded. RESULTS: Thirty-six CEUS-guided musculoskeletal biopsies were performed in 32 patients (mean age 57, range 26-88; 22 males, 10 females). All procedures were performed using 16-gauge biopsy needles, and all procedures provided adequate samples for pathologic analysis as per the final pathology report. Between two and seven core specimens were obtained (mean 3.7). In 30/36 cases (83%), a contrast-enhanced MRI was obtained prior to biopsy, and 10/30 (33%) of these cases showed imaging features suspicious for necrosis. In 15/36 cases, surgical resection was performed, and the core biopsy and surgical resection specimens were concordant in 14/15 cases (93%). One patient noted transient leg discomfort at the time of microbubble bursting. Otherwise, no adverse reactions or procedural complications were observed. CONCLUSION: CEUS is an accurate way to safely target representative areas of soft tissue lesions for biopsy and can be implemented in a busy interventional clinic. Our early experience has shown this to be a promising technique, especially in targeting representative areas of heterogeneous lesions and lesions with areas of suspected necrosis on prior imaging.

Ultrasound-guided microwave ablation in the treatment of inguinal neuralgia.

Chronic groin pain can be due to a variety of causes and is the most common complication of inguinal hernia repair surgery. The etiology of pain after inguinal hernia repair surgery is often multifactorial though injury to or scarring around the nerves in the operative region, namely the ilioinguinal nerve, genital branch of the genitofemoral nerve, and the iliohypogastric nerve, is thought to be a key factor in causing chronic post-operative hernia pain or inguinal neuralgia. Inguinal neuralgia is difficult to treat and requires a multidisciplinary approach. Radiologists play a key role in the management of these patients by providing accurate image-guided injections to alleviate patient symptoms and identify the pain generator. Recently, ultrasound-guided microwave ablation has emerged as a safe technique, capable of providing durable pain relief in the majority of patients with this difficult to treat condition. The objectives of this paper are to review the complex nerve anatomy of the groin, discuss diagnostic ultrasound-guided nerve injection and patient selection for nerve ablation, and illustrate the microwave ablation technique used at our institution.

Intra-session and inter-rater reliability of spatial frequency analysis methods in skeletal muscle.

Spatial frequency analysis (SFA) is a quantitative ultrasound (US) method originally developed to assess intratendinous tissue structure. This method may also be advantageous in assessing other musculoskeletal tissues. Although SFA has been shown to be a reliable assessment strategy in tendon tissue, its reliability in muscle has not been investigated. The purpose of this study was to examine the reliability of spatial frequency parameter measurement for a large muscle group within a healthy population. Ten participants with no history of lower extremity surgery or hamstring strain injury volunteered. Longitudinal B-mode images were collected in three different locations across the hamstring muscles. Following a short rest, the entire imaging procedure was repeated. B-mode images were processed by manually drawing a region of interest (ROI) about the entire muscle thickness. Four spatial frequency parameters of interest were extracted from the image ROIs. Intra- and inter-rater reliabilities of extracted SFA parameters were performed. Test-retest reliability of the image acquisition procedure was assessed between repeat trials. Intraclass correlation coefficients showed high intra- and inter-rater reliability (ICC(3,1) > 0.9 for all parameters) and good to moderate test-retest reliability (ICC(3,1) > 0.50) between trials. No differences in parameter values were observed between trials across all muscles and locations (p > 0.05). The high reliability metrics suggest that SFA will be useful for future studies assessing muscle tissue structure, and may have value in assessing muscular adaptations following injury and during recovery.

US-guided Musculoskeletal Interventions in the Hip with MRI and US Correlation.

Hip pain is a commonly reported primary symptom with many potential causes. The causal entity can remain elusive, even after clinical history review, physical examination, and diagnostic imaging. Although there are many options for definitive treatment, many of these procedures are invasive, are associated with risk of morbidity, and can be unsuccessful, with lengthy revision surgery required. Percutaneous musculoskeletal intervention is an attractive alternative to more invasive procedures and an indispensable tool for evaluating and managing hip pain. US is an ideal modality for imaging guidance owing to its low cost, portability, lack of ionizing radiation, and capability for real-time visualization of soft-tissue and bone structures during intervention. The authors review both common and advanced US-guided procedures involving the pelvis and hip, including anesthetic and corticosteroid injections, percutaneous viscosupplementation, platelet-rich plasma injection to promote tendon healing, and microwave ablation for neurolysis. In addition, specific anatomic structures implicated in hip pain are discussed and include the hip joint, iliopsoas bursa, ilioinguinal nerve, lateral femoral cutaneous nerve, greater trochanteric bursa, iliotibial band, ischiogluteal bursa, hamstring tendon origin, piriformis muscle, and quadratus femoris muscle. The relevant US-depicted anatomy and principles underlying technically successful interventions also are discussed. Familiarity with these techniques can aid radiologists in assuming an important role in the care of patients with hip pain. ©RSNA, 2019.

Ultrasound-Guided Microwave Ablation for the Management of Inguinal Neuralgia: A Preliminary Study with 1-Year Follow-up.

PURPOSE: To evaluate the feasibility and efficacy of ultrasound-guided microwave ablation for the treatment of inguinal neuralgia. MATERIALS AND METHODS: A retrospective review of 12 consecutive ultrasound-guided microwave ablation procedures was performed of 10 consecutive patients (8 men, 2 women; mean age, 41 years [range, 15-64 years]), between August 2012 and August 2016. Inclusion criteria for inguinal neuralgia included clinical diagnosis of chronic inguinal pain (average, 17.3 months [range, 6-46 months]) refractory to conservative treatment and a positive nerve block. Pain response-reduction of pain level and duration and percent pain reduction using a 10-point visual analog scale (VAS) at baseline and up to 12 months after the procedure-was measured. Nine patients had pain after the inguinal hernia repair, and 1 patient had pain from the femoral artery bypass procedure. The microwave ablation procedure targeted the ilioinguinal nerve in 7 cases, the genitofemoral nerve in 4 cases, and the iliohypogastric nerve in 1 case. RESULTS: Average baseline VAS pain score was 6.1 (standard deviation, 2.5). Improved pain levels immediately after the procedure and at 1, 6, and 12 months were statistically significant (P = .0037, .0037, .0038, .0058, respectively). Also, 91.7% (11/12) of the procedures resulted in immediate pain relief and at 1 month and 6 months. At 12 months, 83.3% (10/12) of patients had an average of 69% ± 31% pain reduction. Percent maximal pain reduction was 93% ± 14% (60%-100%), and the average duration of clinically significant pain reduction was 10.5 months (range, 0-12 months.). No complications or adverse outcomes occurred. CONCLUSIONS: Ultrasound-guided microwave ablation is an effective technique for the treatment of inguinal neuralgia after herniorrhaphy.

Evidence of Generalized Muscle Stiffness in the Presence of Latent Trigger Points Within Infraspinatus.

OBJECTIVE: To evaluate stiffness of infraspinatus muscle tissue, both with and without latent trigger points, using ultrasound shear wave elastography (SWE). The primary hypothesis is that muscle with a latent trigger point will demonstrate a discrete region of increased shear wave speed. The secondary hypothesis is that shear wave speed (SWS) in the region with the trigger point will be higher in patients compared with controls, and will be similar between the two groups in the uninvolved regions. DESIGN: Case-control. SETTING: Hospital-based outpatient physical therapy center. PARTICIPANTS: Convenience sample (N=18) of patients (6 female, 3 male, mean age=44) (range=31-61y) diagnosed with latent trigger points in infraspinatus and matched controls without trigger points. MAIN OUTCOME MEASURES: Shear wave speed (m/s). RESULTS: SWS of the latent trigger point (mean=4.09±SD1.4 m/s) did not differ from the adjacent muscle tissue (3.92±1.6 m/s, P>.05), but was elevated compared to corresponding tissue in controls (2.8±0.75 m/s, P=.02). SWS was generally greater in patients' uninvolved tissue (3.83±1.6 m/s) when compared to corresponding tissue in controls (2.62±0.2 m/s, P=.05). CONCLUSION: Although discrete regions of increased SWS corresponding to the trigger point were not observed in patients, evidence of generally increased muscle stiffness in infraspinatus was exhibited compared to healthy controls. Further study of additional muscles with SWE is warranted.

US Evaluation of Juvenile Idiopathic Arthritis and Osteoarticular Infection.

Juvenile idiopathic arthritis (JIA) and osteoarticular infection can cause nonspecific articular and periarticular complaints in children. Although contrast material-enhanced magnetic resonance imaging is the reference standard imaging modality, musculoskeletal ultrasonography (US) is emerging as an important adjunct imaging modality that can provide valuable information relatively quickly without use of radiation or the need for sedation. However, diagnostic accuracy requires a systemic approach, familiarity with various US techniques, and an understanding of maturation-related changes. Specifically, the use of dynamic, Doppler, and/or multifocal US assessments can help confirm sites of disease, monitor therapy response, and guide interventions. In patients with JIA, ongoing synovial inflammation can lead to articular and periarticular changes, including synovitis, tenosynovitis, cartilage damage, bone changes, and enthesopathy. Although these findings can manifest in adult patients with rheumatoid arthritis, important differences and pitfalls exist because of the unique changes associated with an immature and maturing skeleton. In patients who are clinically suspected of having osteoarticular infection, the inability of US to evaluate the bone marrow decreases its sensitivity. Therefore, the US findings should be interpreted with caution because juxtacortical inflammation is suggestive, but neither sensitive nor specific, for underlying osteomyelitis. Similarly, the absence of a joint effusion makes septic arthritis extremely unlikely but not impossible. US findings of JIA and osteoarticular infection often overlap. Although certain clinical scenarios, laboratory findings, and imaging appearances can favor one diagnosis over the other, fluid analysis may still be required for definitive diagnosis and optimal treatment. US is the preferred modality for fluid aspiration and administering intra-articular corticosteroid therapy. © RSNA, 2017.

ACR Appropriateness Criteria® Suspected Osteomyelitis, Septic Arthritis, or Soft Tissue Infection (Excluding Spine and Diabetic Foot).

Infection of the musculoskeletal system is a common clinical problem. Differentiating soft tissue from osseous infection often determines the appropriate clinical therapeutic course. Radiographs are the recommend initial imaging examination, and although often not diagnostic in acute osteomyelitis, can provide anatomic evaluation and alternative diagnoses influencing subsequent imaging selection and interpretation. MRI with contrast is the examination of choice for the evaluation of suspected osteomyelitis, and MRI, CT, and ultrasound can all be useful in the diagnosis of soft tissue infection. CT or a labeled leukocyte scan and sulfur colloid marrow scan combination are alternative options if MRI is contraindicated or extensive artifact from metal is present. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Multimodality Imaging of the Painful Elbow: Current Imaging Concepts and Image-Guided Treatments for the Injured Thrower's Elbow.

Elbow pain in overhead sport athletes is not uncommon. Repetitive throwing can lead to chronic overuse and/or acute injury to tendons, ligaments, bones, or nerves about the elbow. A thorough history and physical examination of the thrower's elbow frequently establishes the diagnosis for pain. Imaging can provide additional information when the clinical picture is unclear or further information is necessary for risk stratification and treatment planning. This article focuses on current imaging concepts and image-guided treatments for injuries commonly affecting the adult throwing athlete's elbow.

Reducing Unnecessary Shoulder MRI Examinations Within a Capitated Health Care System: A Potential Role for Shoulder Ultrasound.

PURPOSE: MRI is frequently overused. The aim of this study was to analyze shoulder MRI ordering practices within a capitated health care system and explore the potential effects of shoulder ultrasound substitution. METHODS: We reviewed medical records of 237 consecutive shoulder MRI examinations performed in 2013 at a Department of Veterans Affairs tertiary care hospital. Using advanced imaging guidelines, we assessed ordering appropriateness of shoulder MRI and estimated the proportion of examinations for which musculoskeletal ultrasound could have been an acceptable substitute, had it been available. We then reviewed MRI findings and assessed if ultrasound with preceding radiograph would have been adequate for diagnosis, based on literature reports of shoulder ultrasound diagnostic performance. RESULTS: Of the 237 examinations reviewed, 106 (45%) were deemed to be inappropriately ordered, most commonly because of an absent preceding radiograph (n = 98; 92%). Nonorthopedic providers had a higher frequency of inappropriate ordering (44%) relative to orthopedic specialists (17%) (P = .016; odds ratio = 3.15, 95% confidence interval = 1.24-8.01). In the 237 examinations, ultrasound could have been the indicated advanced imaging modality for 157 (66%), and most of these (133/157; 85%) could have had all relevant pathologies characterized when combined with radiographs. Regardless of indicated modality, ultrasound could have characterized 80% of all cases ordered by nonorthopedic providers and 50% of cases ordered by orthopedic specialists (P = .007). CONCLUSIONS: Advanced shoulder imaging is often not ordered according to published appropriateness criteria. While nonorthopedic provider orders were more likely to be inappropriate, inappropriateness persisted among orthopedic providers. A combined ultrasound and radiograph evaluation strategy could accurately characterize shoulder pathologies for most cases.

Can Sonography Distinguish a Supraorbital Notch From a Foramen?

Diagnostic tools for evaluating the supraorbital rim in preparation for nerve decompression surgery in patients with chronic headaches are currently limited. We evaluated the use of sonography to diagnose the presence of a supraorbital notch or foramen in 11 cadaver orbits. Sonographic findings were assessed by dissecting cadaver orbits to determine whether a notch or foramen was present. Sonography correctly diagnosed the presence of a supraorbital notch in 7 of 7 cases and correctly diagnosed a supraorbital foramen in 4 of 4 cases. We found that sonography had 100% sensitivity in diagnosing a supraorbital notch and foramen. This tool may therefore be helpful in characterizing the supraorbital rim preoperatively and may influence the decision to use a transpalpebral or endoscopic approach for supraorbital nerve decompression as well as the decision to use local or general anesthesia.

In Vivo Measures of Shear Wave Speed as a Predictor of Tendon Elasticity and Strength.

The purpose of this study was to assess the potential for ultrasound shear wave elastography (SWE) to measure tissue elasticity and ultimate stress in both intact and healing tendons. The lateral gastrocnemius (Achilles) tendons of 41 New Zealand white rabbits were surgically severed and repaired with growth factor coated sutures. SWE imaging was used to measure shear wave speed (SWS) in both the medial and lateral tendons pre-surgery, and at 2 and 4 wk post-surgery. Rabbits were euthanized at 4 wk, and both medial and lateral tendons underwent mechanical testing to failure. SWS significantly (p < 0.001) decreased an average of 17% between the intact and post-surgical state across all tendons. SWS was significantly (p < 0.001) correlated with both the tendon elastic modulus (r = 0.52) and ultimate stress (r = 0.58). Thus, ultrasound SWE is a potentially promising non-invasive technology for quantitatively assessing the mechanical integrity of pre-operative and post-operative tendons.

MRI characteristics of healed and unhealed peripheral vertical meniscal tears.

OBJECTIVE: The objective of our study was to retrospectively compare the MRI characteristics of surgically confirmed healed and unhealed peripheral vertical meniscal tears. MATERIALS AND METHODS: The study group consisted of 64 patients with 86 peripheral vertical meniscal tears diagnosed on MRI who subsequently underwent knee surgery. The MRI examinations were retrospectively reviewed to assess the following tear characteristics: tear location relative to the meniscocapsular junction, tear width, tear length, tear extension through one or both surfaces, sequences on which tear was visualized, signal intensity of tear on T2-weighted imaging, and presence of low-signal-intensity strands bridging the tear on T2-weighted imaging. Multivariate logistic regression models were used to determine whether MRI characteristics could be used to distinguish between healed and unhealed tears at surgery. RESULTS: Tear location was the most significant characteristic (p<0.001) for distinguishing between healed and unhealed tears: 17 of 18 (94.4%) tears located at the meniscocapsular junction of the medial meniscus were healed and 15 of 68 (22.1%) tears not located at the meniscocapsular junction were healed. For tears not located at the meniscocapsular junction, MRI characteristics significantly associated with healed tears included a tear width of less than 2 mm (p=0.01), tear visualized only on intermediate-weighted imaging (p=0.01), tear showing intermediate or bright signal intensity on T2-weighted imaging (p=0.06), and low-signal-intensity strands bridging the tear on T2-weighted imaging (p<0.001). CONCLUSION: Most peripheral vertical tears at the meniscocapsular junction of the medial meniscus spontaneously heal. The MRI characteristics of tears not located at the meniscocapsular junction can help distinguish between healed and unhealed tears.

High resolution ultrasound features of prostatic rib metastasis: a prospective feasibility study with implication in the high-risk prostate cancer patient.

OBJECTIVE: In a prior study, high resolution ultrasound (US) was shown to be accurate for evaluating rib metastasis detected on bone scan. However, that study did not address the specific US appearance typical of osteoblastic rib metastasis. Our objective was to determine the specific US imaging appearance of osteoblastic prostate carcinoma rib metastasis using osteolytic renal cell carcinoma rib metastasis as a comparison group. MATERIALS AND METHODS: The Institutional Review Board approval and informed consent were obtained for this prospective feasibility study. We performed high resolution US of 16 rib metastases in 4 patients with prostate carcinoma metastases and compared them to 8 rib metastases in 3 male patients with renal cell carcinoma. All patients had rib metastases proven by radiographs and computed tomography (CT). High resolution US scanning was performed by a musculoskeletal radiologist using a 12-5 MHz linear-array transducer. Transverse and longitudinal scans were obtained of each rib metastasis. RESULTS: All 16 prostate carcinoma metastases demonstrated mild cortical irregularity of the superficial surface of the rib without associated soft tissue mass, cortical disruption, or bone destruction. 7 of 8 (88%) renal cell carcinoma rib metastases demonstrated cortical disruption or extensive bone destruction without soft tissue mass. One of 8 (12%) renal cell carcinoma rib metastases demonstrated only minimal superficial cortical irregularity at the site of a healed metastasis. CONCLUSION: Osteoblastic prostate carcinoma rib metastases have a distinctive appearance on US. Our success in visualizing these lesions suggests that US may be a useful tool to characterize isolated rib abnormalities seen on a bone scan in high-risk prostate cancer patients who are being evaluated for curative surgery or radiation treatment.

Accuracy of sonographic diagnosis of superficial masses.

OBJECTIVES: The purpose of this study was to retrospectively review the diagnostic accuracy of sonography in the evaluation of superficial masses with surgical and histologic findings as the reference standard. METHODS: Institutional Review Board approval was obtained, informed consent was waived, and Health Insurance Portability and Accountability Act compliance was maintained. Seventy-two superficial masses in 62 patients were examined sonographically by a single radiologist (reader 1) and subsequently underwent surgical therapy. Three radiologists experienced in sonography, blinded to the original interpretation and surgical findings, retrospectively and independently reviewed the sonographic images and assigned the cases to 1 of 14 diagnostic categories. For all lesions, the rendered diagnosis was compared with the reference standard to determine concordance. For the specific diagnosis of lipoma, sensitivity, specificity, and accuracy were assessed for all readers individually and collectively. RESULTS: Surgery and histolopathologic analysis yielded 39 lipomas, 6 hernias, 4 foreign bodies, 4 hemangiomas, and 19 other nonlipomatous lesions, including 1 malignancy. The rendered diagnosis was concordant with the reference standard in 93% of cases for reader 1 and in 89% of cases for all readers. The sensitivity, specificity, and accuracy for the diagnosis of lipoma were 92%, 100%, and 96% for reader 1 and 96%, 97%, and 96% for all readers. CONCLUSIONS: Sonography has high accuracy in the evaluation of superficial masses, particularly lipomas.