Magnetic resonance imaging of the shoulder joint.

Because the shoulder is the most mobile joint in the body, it is naturally predisposed to several disorders. The most commonly encountered disorders requiring diagnostic imaging are rotator cuff disease and glenohumeral instability. Plain film radiography and arthrography have for many years been the mainstays of shoulder imaging. CT added a third dimension to shoulder imaging, improving its sensitivity with respect to glenoid labral pathology. Ultrasonography of the rotator cuff showed early promise in noninvasive evaluation of cuff tears, but it did not gain universal acceptance because of various negative factors, including inadequate visualization of the cuff, poor results regarding partial tears, and most importantly, operator dependency. The development of MR imaging afforded the radiologist improved comprehensive visualization of the shoulder joint in a noninvasive manner.