Plain film radiographic evaluation of the shoulder should include frontal examinations with internal and external humeral rotation. If there is a question of instability or dislocation, an axillary view, a scapular Y view, or both should be obtained. There have been several reports that recommend the use of a 30-degree caudad-angled radiograph or a suprascapular outlet view for the assessment of the anterior acromion in cases of suspected shoulder impingement. Since these are special views, they must be ordered as routine shoulder radiographs do not include axillary or suprascapular outlet views. The RRL for plain film radiographic examinations of the shoulder is less than 0.1 mSv, which is considered minimal.

MRI has become valuable in evaluating a host of shoulder abnormalities very familiar to the physiatrist. These include impingement syndrome, other rotator cuff abnormalities, instability syndrome, and bicipital tendon abnormalities. It is also useful in demonstrating arthritic changes, occult fractures, ischemic necrosis, and intra-articular bodies. MRI with intra- articular contrast is now considered the modality of choice for the evaluation of labral and capsular pathology. The use of MRI for shoulder evaluation avoids radiation exposure to the nearby thyroid gland, which can occur with CT examinations.The excellent visualization of marrow by MRI permits early diagnosis of ischemic necrosis, infection, and primary or metastatic tumors.

Because of the oblique orientation of the scapula on the chest wall and the consequent anterolateral facing direction of the glenoid, the direct multiplanar imaging capability of MRI provides optimal visualization of all the important shoulder structures. An oblique coronal image parallel to the plane of the scapula provide full-length views of the rotator cuff musculature, especially the supraspinatus and is the best plane for the evaluation of injuries to the biceps-labral complex (BLC) (Fig. 6-1A and B). Coronal oblique images can also provide information about the presence of impingement upon the supraspinatus by the acromion and osteophytes in the presence of acromioclavicular joint osteoarthritis. Oblique sagittal imaging planes parallel to the glenoid provide cross-sectional views of the rotator cuff apparatus and evaluates the anatomical configuration of the coracoacromial arch and the presence of impingement (Fig. 6-1D). Axial imaging planes provide good visualization of the anterior and posterior capsular apparatus, glenoid labrum, bony glenoid rim, and humeral head (Fig. 6-1C).

FIGURE 6-1. Normal shoulder MR images. A: An axial scout film with cursors displays the oblique coronal planes parallel to the plane of the scapula, which allow optimal visualization of the supraspinatus. B: An oblique coronal image demonstrates the supraspinatus muscle belly (SsB), supraspinatus tendon (SsT), subacromial-subdeltoid fat plane (FP), acromioclavicular joint (ACJ), deltoid muscle (D), articular cartilage of humeral head and glenoid (AC), glenoid (G), and humeral head (H). C: An axial image displays humeral head (H), glenoid (G), glenoid labrum (L), the inferior glenohumeral ligament (IGL), deltoid muscle (D), subscapsularis tendon (ScT), and biceps tendon (BT). D: A sagittal section demonstrates good resolution of the coracoacromial ligament (CAL) extending from the coracoid process (CP) to the acromion; coracoid process (CP), supraspinatus (SS), infraspinatus (IS).


Source: Physical Medicine and Rehabilitation - Principles and Practice

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