Magnetic resonance imaging of the shoulder: rationale and current applications

Abstract

Because it can demonstrate a wide range of tissue contrast with excellent resolution, magnetic resonance (MR) imaging has revolutionized imaging in many areas of the musculoskeletal system and has generated excitement among those interested in the painful shoulder. Shoulder impingement syndrome and glenohumeral instability constitute the two major categories of shoulder derangements. Correct diagnosis requires the use of appropriate pulse sequences and imaging planes, proper patient positioning, and a satisfactory surface coil. In addition the imager must have a thorough understanding of shoulder anatomy and pathology. We present a summary of the current status of MR imaging of the shoulder including technical, anatomic, and pathologic considerations and a review of the pertinent literature.

MR imaging of the rotator cuff: peritendinous and bone abnormalities in an asymptomatic population.

“…MR MR imaging has been shown to be accurate in the detection of shoulder pathology, particularly in the evaluation of rotator cuff disease [1][2][3][4][5][6][7][8][9][10]. Recent studies have questioned the clinical significance of the MR imaging diagnosis of tendinopathy by revealing similar MR signal findings in a large number of asymptomatic shoulders [11][12][13][14][15].…”

Effect of field of view on MR diagnosis of rotator cuff tears

“…There are two main reasons for this. First, the inherent S/N ratio of shoulder images obtained with a standard single-loop surface coil is poorer than in the knee, where a circumferential sendand-receive coil can be used [6,12]. Second, some image blurring, due mainly to respiratory motion, occurs because the standard single-loop surface coil does not rigidly immobilize the shoulder [12].…”

“…First, the inherent S/N ratio of shoulder images obtained with a standard single-loop surface coil is poorer than in the knee, where a circumferential sendand-receive coil can be used [6,12]. Second, some image blurring, due mainly to respiratory motion, occurs because the standard single-loop surface coil does not rigidly immobilize the shoulder [12]. When imaging body parts affected by motion, improving spatial resolution can further degrade the image as pixel sizes are decreased relative to the amount of displacement [2].…”

“…In this study, we have demonstrated a statistically significant improvement in specificity only when the voxel size is reduced from 4.7 to 2.6 mm 3 and the NEX are left unchanged. Similar voxel sizes, from 6.1 mm to 2.2 mm 3, have been used in many of the previously published papers on the accuracy of MR in the diagnosis of rotator cuff tears [7,9,12,13]. The purpose of our study was not to document the diagnostic efficacy of the current, smaller FOVs, but instead to determine whether improvements in resolution at the expense of the S/N ratio in shoulder MR changed diagnostic accuracy.…”

“…Although the sizes of the rotator cuff tears were graded as part of a different project, for the purposes of this study the cuff grades were condensed into either "intact" or "partial" or "full-thickness" tear based on previously published criteria for gradient echo imaging [11,12]. Sensitivity and specificity were calculated using the surgical findings as the gold standard.…”