MRI of the Extensor Tendons of the Wrist.

OBJECTIVE: This article reviews the normal anatomy of the extensor tendons of the wrist as well as the clinical presentation and MRI appearances of common tendon abnormalities, such as tears, tenosynovitis, intersection syndromes, and associated or predisposing osseous findings. Treatment options are also discussed. CONCLUSION: We review the anatomy and normal MRI appearance of the clinically important dorsal extensor tendons of the wrist, in addition to the spectrum of abnormalities associated with these tendons.

ECU tendon "dislocation" in asymptomatic volunteers.

OBJECTIVE: Assess extensor carpi ulnaris (ECU) tendon position in the ulnar groove, determine the frequency of tendon "dislocation" with the forearm prone, neutral, and supine, and determine if an association exists between ulnar groove morphology and tendon position in asymptomatic volunteers. MATERIALS AND METHODS: Axial proton density-weighted MR was performed through the distal radioulnar joint with the forearm prone, neutral, and supine in 38 asymptomatic wrists. The percentage of the tendon located beyond the ulnar-most border of the ulnar groove was recorded. Ulnar groove depth and length was measured and ECU tendon signal was assessed. RESULTS: 15.8 % of tendons remained within the groove in all forearm positions. In 76.3 %, the tendon translated medially from prone to supine. The tendon "dislocated" in 0, 10.5, and 39.5 % with the forearm prone, neutral and supine, respectively. In 7.9 % prone, 5.3 % neutral, and 10.5 % supine exams, the tendon was 51-99 % beyond the ulnar border of the ulnar groove. Mean ulnar groove depth and length were 1.6 and 7.7 mm, respectively, with an overall trend towards greater degrees of tendon translation in shorter, shallower ulnar grooves. CONCLUSIONS: The ECU tendon shifts in a medial direction when the forearm is supine; however, tendon "dislocation" has not been previously documented in asymptomatic volunteers. The ECU tendon medially translated or frankly dislocated from the ulnar groove in the majority of our asymptomatic volunteers, particularly when the forearm is supine. Overall greater degrees of tendon translation were observed in shorter and shallower ulnar grooves.

Imaging of cysts and bursae about the shoulder.

A variety of fluid and fluid-like containing structures can be seen on routine MR imaging of the shoulder including bursal effusions and cystic lesions often in association with rotator cuff tears and impingement. Given its high soft tissue contrast and multiplanar imaging capabilities, MR imaging is the modality of choice in quantifying size, confirming fluid composition, assessing anatomical relationship to the glenohumeral joint, and determining the presence/absence of accompanying intra-articular abnormalities in association with the bursal and juxta-articular cystic findings.