MR arthrography in the differential diagnosis of type II superior labral anteroposterior lesion and sublabral recess

OBJECTIVE. The objective of our study was to assess the utility of five MR arthrographic findings in differentiating type II superior labral anteroposterior (SLAP) lesion from superior sublabral recess. MATERIALS AND METHODS. The MR arthrograms of 55 patients (57 cases) with either type II SLAP lesion (34 cases) or superior sublabral recess (23 cases) who underwent arthroscopic surgery and MR arthrography were retrospectively reviewed. Two independent reviewers searched for the extension, direction, and shape of high signal intensity in the superior labrum on MR arthrograms. In addition, the presence of concomitant anterosuperior labral tear and anteroposterior extension of high signal intensity on axial images was evaluated. The frequencies of these findings in cases of type II SLAP lesion and sublabral recess were evaluated, and the statistical significance of each finding in differentiation of the two groups was assessed. RESULTS. Extension of high signal intensity behind the biceps anchor that extended beneath the labrum on fat-saturated oblique coronal T1-weighted images was found in 33 (97%) of the cases of type II SLAP lesion and 21 (91%) of the cases of sublabral recess. Laterally curved high signal intensity was found in 17 (50%) of the cases of type II SLAP lesion but in only four (17%) of the cases of sublabral recess. Globular or irregular shape of the superior labrum was present in 22 (65%) of the cases of type II SLAP lesion and in 10 (43%) of the cases of sublabral recess. Concomitant anterosuperior labral tear was seen in 14 (41%) of the cases of type II SLAP lesion but in only two (8.7%) of the cases of sublabral recess. Anteroposterior extension of high signal intensity in the superior labrum on fat-saturated axial T1-weighted images was detected in 33 cases of type II SLAP lesion (97%) and in 14 cases of sublabral recess (61%). CONCLUSION. Although the MR arthrographic findings were similar for type II SLAP lesion and sublabral recess, laterally curved high signal intensity on oblique coronal images, concomitant anterosuperior labral tear, and anteroposterior extension of high signal intensity on axial images were helpful findings in the diagnosis of type II SLAP lesion.