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. Key words: atrophy; muscles; rotator cuff; shoulder; sonography. onography has proven to be both sensitive and specific in assessing the integrity of the rotator cuff tendons. 1 Although much has been published on sonographic evaluation of the cuff tendons, there are only a few reports in the imaging literature mentioning the rotator cuff muscles. 2,3The high-resolution capabilities of sonography afford detailed delineation of internal muscle architecture. The normal pennate structure of skeletal muscle, including hypoechoic muscle bundles and hyperechoic investing fibroadipose septa of the perimysium, are easily recognized on sonography.4 Alterations in muscle echo texture and morphologic characteristics can indicate a number of pathologic conditions, both focal, such as tears and hematoma formation, as well as more diffuse processes, including myositis and atrophy. [5][6][7] Although diffuse increased muscle echogenicity may have many etiolo-

Computed tomography fluoroscopic-guided musculoskeletal biopsies show a high diagnostic yield and are accurate and safe. The biopsy results are similar or superior to other published reports using conventional CT guidance with only a small overall fraction being nondiagnostic. The benefits of real-time imaging are at the cost of operator exposure to ionizing radiation and the risk of potentially high exposures to both patient and operator. The impact on indications for which lesions are most amenable to percutaneous biopsy using CT fluoroscopy and procedure time has yet to be determined.

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