US of the Rotator Cuff: Pitfalls, Limitations, and Artifacts

Abstract

High-resolution ultrasonography (US) has gained increasing popularity as a diagnostic tool for assessment of the soft tissues in shoulder impingement syndrome. US is a powerful and accurate method for diagnosis of rotator cuff tears and other rotator cuff abnormalities, provided the examiner has a detailed knowledge of shoulder anatomy, uses a standardized examination technique, and has a thorough understanding of the potential pitfalls, limitations, and artifacts. False-positive sonographic findings of rotator cuff tears can be caused by the technique (anisotropy, transducer positioning, acoustic shadowing by the deltoid septum), by the anatomy (rotator cuff interval, supraspinatus-infraspinatus interface, musculotendinous junction, fibrocartilaginous insertion), or by disease (criteria for diagnosis of rotator cuff tears, tendon inhomogeneity, acoustic shadowing by scar tissue or calcification, rotator cuff thinning). False-negative sonographic findings of rotator cuff tears can be caused by the technique (transducer frequency, suboptimal focusing, imaging protocol, transducer handling), by the anatomy (nondiastasis of the ruptured tendon fibers, posttraumatic obscuration of landmarks), by disease (tendinosis, calcifications, synovial proliferation, granulation or scar tissue, bursal thickening, massive rotator cuff tears), or by patient factors (obesity, muscularity, limited shoulder motion).

Equívocos diagnósticos envolvendo as tendinites: impacto médico, social, jurídico e econômico

“…Several factors can contribute for the false-positive results of tendon US scan, especially in the shoulder, such as the technique used or angle variations during the exam, personal criteria used in the conclusion, the presence of common artifacts, and others. 64 A study with asymptomatic individuals showed that the US scan can detect fluid or apparently inflammatory changes in up to 85% of bursas, 27% of biceps tendons, 77% of suprapatellar recesses, 16% of popliteal areas, and 24% of retro calcaneal bursas, besides other articular areas and tendon sheaths, with a variation of up to 28% among US scans. 65 In other words, an US scan report can just mention that "fluid was found" or "findings compatible with inflammatory changes", wrongly concluding that bursitis, tendonitis, and other changes are present where, very often, they do not exist or whose finding is not pathologic, contributing for the false-positive diagnosis of tendonitis.…”

US anatomy of the shoulder: Pictorial essay

“…It extends forward and downward and covers the bicipital groove, while its rear and side boundaries may vary. However, it generally reaches a level situated about 3 cm over the greater tuberosity of the humerus [6]. It may lie in continuity with the subcoracoid bursa.…”

“…7) is a synovial structure situated below the clavicle, acromion and coracoacromial ligament and above the rotator cuff [3,5,6]. Under physiological conditions it does not communicate with the glenohumeral joint but it may communicate with the joint cavity after a full-thickness supraspinatus tendon tear [1,3,5,6].…”

“…The bursa is surrounded by a thin layer of peribursal fat, and under pathological conditions it is easily detectable at US examination (Fig. 7) [1,6]; it is situated deep beneath the deltoid muscle and under the acromion and coracoacromial ligament in front of the supraspinatus tendon. It extends forward and downward and covers the bicipital groove, while its rear and side boundaries may vary.…”

“…8) is situated below and medially to the acromion near the joint capsule and the subscapularis tendon [1]. Under physiological conditions it does not communicate with the joint cavity [6]. Both bursae are there to reduce friction between the tendons and the surrounding osteofibrous structures.…”