Faculty Bibliography

Ultrasound is well suited to evaluate a wide variety of abnormalities involving skeletal muscle, including traumatic injuries, inflammatory or infectious myositis, atrophy, and tumors. Ultrasound can accurately localize and characterize a lesion, or grade the severity of injury. The unique ability of ultrasound to assess the dynamic function of muscles on the real-time or perform Doppler evaluation of vascularity provides insights that are not readily obtained with other imaging modalities. With ultrasound, image-guided biopsy can be performed in conjunction with a diagnostic evaluation. This article presents a pictorial review of lesions and abnormalities involving skeletal muscles, and discusses characteristic findings, classifications, and imaging methods.

OBJECTIVE: The purpose of this study was to evaluate the utility of color B-mode imaging with contrast optimization in evaluating low-contrast lesions of the foot and ankle (Morton neuromas and plantar fasciitis). METHODS: The sonographic examinations of 49 consecutive patients with a diagnosis of plantar fasciitis or Morton neuroma imaged with both conventional gray scale imaging and color B-mode imaging with contrast optimization (Photopic; Siemens Medical Solutions, Mountain View, CA) were reviewed. In every patient, matched pairs of images obtained with conventional gray and color maps (Photopic) were acquired and stored as DICOM (Digital Imaging and Communications in Medicine) images on a sonographic workstation. Each image was assessed independently by 2 musculoskeletal radiologists trained in musculoskeletal sonography for overall image contrast (lesion to background), conspicuity of regional tissue boundaries, visualization of deep tissue boundaries, and how well the internal characteristics of the structure were visualized. RESULTS: Three-way analysis of variance showed that Photopic imaging resulted in statistically significantly improved overall image contrast, definition of regional soft tissue boundaries, including deep soft tissue boundaries, and depiction of the internal characteristics of the structure being examined. CONCLUSIONS: Color imaging with contrast optimization improves overall image contrast and better defines deep soft tissue boundaries and the internal morphologic characteristics of Morton neuromas and the plantar fascia compared with conventional gray scale imaging.

OBJECTIVE: To understand a linear artifact that projects deep to reflective structures that move rapidly while using tissue harmonic imaging with pulse inversion (PI) sonography. We hypothesize that this artifact is due to a cancellation error between firings in PI imaging, and it is, therefore, similar in generation to the twinkling artifact in color Doppler sonography. This artifact could be studied with the use of surfaces of different roughness to represent different rates of motion, in which roughness corresponds to spatial fluctuations in surface height. Given very slight variations in beam focusing as occurs with sonographic imaging arrays, these spatial fluctuations translate into temporal fluctuations in the received signal as would occur with tissue motion. METHODS: We scanned 4 different sandpaper grits and a smooth surface through a water path using fundamental and PI mode, 1- and 2-pulse techniques, respectively. The sandpaper and the smooth surface were scanned through a water path at mechanical indices of 0.1 to 0.7. Four independent images were subtracted pairwise to remove nonfluctuating signals. These noise pixels were counted and analyzed. RESULTS: Analysis of variance showed that the noise generated behind the different surfaces was highly significantly different. Two-tailed t tests generally showed significant differences in the quantity of noise between fundamental and harmonic imaging behind the roughest 3 grades of sandpaper. A multiple regression model showed significantly greater slopes for harmonic imaging for all grades of sandpaper and the smooth surface. CONCLUSIONS: The noise and, by extension, the linear streak artifact in musculoskeletal imaging are dependent on the mechanical index and are functions of sandpaper roughness. This would be equivalent to a subtraction error between 2 firings due to soft tissue motion, and the artifact may be a way to identify rapid soft tissue motion in PI images.

OBJECTIVE: To describe the utility of sonography in visualizing muscle atrophy during routine sonographic examination of the shoulder for evaluation of the rotator cuff tendons. METHODS: A retrospective review of 199 shoulder sonographic examinations performed by 2 musculoskeletal radiologists trained in musculoskeletal sonography with knowledge of the typical sonographic findings of muscle atrophy was performed. Reports were reviewed for the presence of muscle atrophy. If atrophy was present, the reports from those examinations were rereviewed for concomitant rotator cuff abnormalities. RESULTS: Forty-five examinations (23%) showed atrophy in at least 1 muscle on the basis of the criteria of increased echogenicity and decreased bulk. There were a total of 81 individual muscles that showed atrophy, with the following distribution: 16% supraspinatus (n = 13), 31% infraspinatus (n = 25), 36% teres minor (n = 29), 2% subscapularis (n = 2), and 6% biceps brachii (n = 5). In 34 of the 45 examinations with muscle atrophy, there were 57 concomitant full-thickness tendon tears: 64% supraspinatus (n = 29), 38% infraspinatus (n = 17), 7% subscapularis (n = 3), 0% teres minor (n = 0), 16% long head of biceps (n = 7), and 2% deltoid (n = 1). CONCLUSIONS: Although primary sonographic evaluation of the painful shoulder concentrates on the tendons of the rotator cuff, we suggest that examination of the muscles should become a standard component of the comprehensive shoulder sonographic examination, particularly given the potential clinical implications of muscle atrophy on the outcome of rotator cuff surgery.

OBJECTIVE: The purpose of our study was to describe the sonographic appearance of cubital bursitis in three patients and to illustrate the use of sonographic guidance for therapeutic injections. CONCLUSION: Cubital bursitis, a rare but painful condition of the elbow, can be diagnosed with sonography. Cubital bursitis is seen as distention of the bicipitoradial bursa in the proximal forearm, occasionally with fluid or complex synovial debris in more severe cases. Power Doppler imaging can aid in providing information about active inflammation. Two patients in our series were treated using sonographically guided decompression of the bursa and steroid injection with good clinical results.

OBJECTIVE: The purpose of this study is to describe the sonographic appearance of injuries of the ulnar collateral ligament (UCL) of the elbow. DESIGN AND PATIENTS: Eight non-professional male baseball pitchers, ages 13-35 years, with medial elbow pain and clinical suspicion of ulnar collateral ligament injury, were referred for imaging. All eight underwent sonography of the affected and contralateral asymptomatic elbow, and six also underwent MR imaging. Neither valgus stress nor power Doppler was used during the sonographic examinations. Time from onset of symptoms to imaging was 1.5 weeks to 6 months. Three patients had surgical confirmation of their injuries, with time from imaging to surgery of 2 days to 9 months. RESULTS: In four patients, the UCL was ruptured, manifest sonographically in three cases as discontinuity of the normally hyperechoic ligament with anechoic fluid in the gap and in one case as non-visualization of the ligament with heterogeneous echogenicity in the expected location of the ligament. Two adolescent patients had avulsions of the UCL from the medial epicondyle, with sonographic demonstration of the avulsed echogenic bony fragment in both cases. One patient had a mild sprain, manifest as mild thickening and decreased echogenicity of the ligament sonographically compared with the contralateral normal elbow, with mild surrounding hypoechoic edema. The eighth patient had a small partial tear of the deep surface of the distal aspect of the ligament, visualized as a hypoechoic focus between the deep surface of the ligament and its ulnar attachment. CONCLUSION: Tears of the ulnar collateral ligament are manifested sonographically as non-visualization of the ligament or alteration of the normal morphology.

OBJECTIVE: To present the power Doppler findings and evaluate the hypoechoic rim in increasing the conspicuity of foreign bodies detected on sonography and to correlate the sonographic and histopathologic findings. METHODS: Between 1998 and 2001, all sonographic examinations for evaluation of possible foreign bodies were reviewed retrospectively. Patients who had surgical exploration and pathologic evaluation were included in the study. Gray scale and power Doppler examinations were performed with high-frequency linear array transducers. Histologic evaluation was then correlated with the sonographic findings. RESULTS: Twenty-five patients were referred for evaluation of possible foreign bodies. Twelve patients underwent surgery and had pathologic correlation. Sonography had sensitivity of 92% for the overall detection of foreign bodies. There were 2 false-positive findings in which discrete foreign bodies were not seen at gross inspection, but inflammation and scar tissue were present at histologic examination. Pathologic findings were thought to represent chronic foreign body reactions. Hypervascularity immediately surrounding the foreign bodies was shown on power Doppler imaging in all cases, correlating with granulation tissue and neovascularity on pathologic examinations. The hypoechoic halo was shown in all but 2 cases and correlated with fibrinous exudate, granulation tissue, and collagenous capsule formation. CONCLUSIONS: Sonography is an effective and sensitive tool for the detection of soft tissue foreign bodies. The use of power Doppler imaging may aid in detection of possible foreign bodies by increasing the conspicuity of both the hypoechoic halo and the foreign body itself.

OBJECTIVE: We investigated the ability of sonography to reveal the polyethylene liner used in total knee arthroplasty with the hopes of establishing a possible relationship between the sonographic measurement of the actual thickness of the polyethylene liner and the estimated thickness based on conventional radiography. MATERIALS AND METHODS: Twenty-four consecutive patients who were referred for Doppler screening for deep venous thrombosis after total knee arthroplasty were evaluated. The polyethylene liner was identified on sonography, and three measurements were obtained from four locations: anteromedial joint line (just medial to the midline incision), along the medial joint line, anterolateral joint line (just lateral to the midline incision), and along the lateral joint line. These sonographic measurements were compared with radiographic measurements of the radiolucent polyethylene liner and with the manufacturers' stated size of the polyethylene liner. Linear regression analyses were then performed. RESULTS: The polyethylene liner is seen on sonography as a strong linear echogenic interface with posterior acoustic shadowing. Linear regression analyses showed a high correlation (r = 0.8) between the sonographic measurements and the radiographic measurements. A relatively poor correlation (r = 0.2) was noted between the manufacturers' stated size of the liner and the sonographic measurements. CONCLUSION: We found that the polyethylene liner used in total knee arthroplasty can be clearly identified during sonographic evaluation of the knee. We also found a high correlation between the longitudinal measurement of the polyethylene liner with the thickness of the radiolucent polyethylene as measured on conventional radiographs. We propose that sonography could potentially be a useful noninvasive imaging modality to screen for subtle cases of polyethylene wear.