The normal shoulder: common variations that simulate pathologic conditions at MR imaging.

Abstract

The appearance of the supraspinatus tendon and anterior capsular mechanism was analyzed in 60 asymptomatic shoulders with magnetic resonance (MR) imaging. The images were reviewed with special attention to findings that simulate pathologic conditions, as defined by means of currently accepted criteria. On T1-weighted and proton-density (PD) spin-echo (SE) images, intermediate signal intensity was present within the supraspinatus tendon in most shoulders. Focal signal intensity within the distal tendon was particularly common finding, being present in 95% (57 of 60) of shoulders on PD images. Focal obliteration of the subacromial-subdeltoid fat stripe and acromioclavicular joint arthrosis were seen in 95% (57 of 60) and 48% (29 of 60) of the subjects, respectively. There was considerable variation in the shape of the anterior glenoid labrum-glenohumeral ligament (GHL) complex. The labrum may appear triangular, round, crescentic, or absent. The middle and inferior GHLs lie in proximity to the upper half of the anterior labrum; the cleavage plane between the ligaments and the labrum can mimic a tear at MR imaging.

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

“…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]. These studies have also called into question the utility of some of the secondary findings associated with rotator cuff disease because of their prevalence in asymptomatic volunteers [11][12][13][14][15]. For the same large population of asymptomatic volunteers as was used for the present study, we reported a high incidence of MR imaging-diagnosed tendon abnormalities in a recent publication in the orthopedic litematume [16] ing from the acromion tip [9].…”

Tendon of the normal supraspinatus muscle: correlations between MR imaging and histology

“…These constraints, which are combined during the play of the articulation, are of three kinds: (1) traction constraints during muscular contraction; (2) compression constraints when 334 N Gagey et al: Tendon of the normal supraspinatus muscle the humeral head is forced against the acromion, probably associated with ischemia in the narrowest zone of the subacromial corridor [7]; (3) torsion constraints during movements of forced medial and lateral rotation. These constraints are maximal in the axis of traction of the supraspinatus m., which is defined by the presence within the muscle belly of a bulky tendon directed laterally and forward to become attached to the most anterior part of the greater tubercle [8,4,12].…”

Gradient-echo versus fat-suppressed fast spin-echo MR imaging of rotator cuff tears.

“…Interpretations were done according to previ ouslydescribed criteriafor MR imagingof rotator cuff disorders[1â€"6, 9, 21, 221andof the normal shoulder [19,23,24]. A tendon was diagnosed as normal when it appeared to be hypointense on all pulsesequences andhadnocontourabnormalityor intrinsicsignal abnormality.…”