Shoulder MRI remains one of the most common indications for orthopedic and sports medicine patient visits. Frequently encountered pathologies include rotator cuff and biceps arthropathy, anteroinferior glenohumeral instability, labral tear, and osteoarthrosis of the acromioclavicular and glenohumeral joints. An MRI examination of the shoulder provides superior evaluation of soft tissue structures and pathologies when compared with CT and x-ray.1 A fundamental understanding of shoulder MRI, then, can be of great aid to both the practicing clinician and musculoskeletal radiologist in diagnosing various pain generators.
MRI of the shoulder is typically performed in three orthogonal planes—axial, coronal, and sagittal—with respect to the glenohumeral joint. A coronal sequence should be perpendicular to the short axis of the glenoid articular surface (Figure 12-1A), while the sagittal is parallel to the short axis of the glenoid articular surface (Figure 12-1B), and the axial is perpendicular to the long axis of the glenoid articular surface (Figure 12-1C). Both fat- and fluid-sensitive sequences are obtained in all three orthogonal planes. Fat-sensitive sequences are best for detailed anatomy and osseous evaluation, while fluid-sensitive sequences are best for evaluation of tendons or labrum. In certain instances, such as tumor evaluation, intravenous contrast may be administered. For MR arthrography, which is best for visualizing labral pathologies, dilute intra-articular gadolinium is administered into the joint prior to MRI.2,3
Standard MR sequences of the shoulder. Coronal (A), sagittal (B), and axial (C) sequences of the shoulder should be oblique, in the planes of the glenohumeral joint. The coronal sequence (A) should be perpendicular to the glenoid articular surface as shown on the axial image (white dashed line). The sagittal sequence (B) should be parallel to the glenoid articular surface as shown on the axial image (white line). The axial sequence (C) should be perpendicular to the glenoid articular surface as shown on the coronal image (dashed line).
A structured approach to evaluation and interpretation of shoulder MRI is crucial. In our practice, we organize the shoulder report into the following sections: (1) acromioclavicular (AC) joint, (2) rotator cuff tendons and muscles, (3) biceps, (4) labrum, (5) glenohumeral joint, and (6) miscellaneous.
The acromion has been classified into four morphologic types: type 1 (flat), type 2 (curved downward), type 3 (hooked downward anteriorly), and type 4 (curved upward) (Figure 12-2). The presence of an unfused acromial apophysis (os acromiale) may have clinical symptomatology and should be included in evaluation.4 Often, AC pathology is associated with bursal sided cuff tear due to clinical entity of subacromial ...