Width of High Signal and Extension Posterior to Biceps Tendon as Signs of Superior Labrum Anterior to Posterior Tears on MRI and MR Arthrography

Abstract

The purpose of our study was to determine the accuracy of two signs for superior labrum anterior to posterior (SLAP) tears: increased width of high signal between the superior labrum and glenoid, and high signal posterior to the biceps tendon. Forty-one patients with SLAP tears and 40 patients without a tear at surgery who had undergone MRI or MR arthrography were retrospectively evaluated. The MR studies were combined and interpreted in a blinded manner. The reviewers measured the width of high signal that extended to the articular surface on oblique coronal images and determined whether the high signal extended posterior to the biceps. A Student's t test was used to determine statistical significance between the means of the signal width. High-signal width was greater in patients with a SLAP tear than in the control group on both MRI and MR arthrography (both p = 0.003). The sensitivity and specificity of at least 2.0 mm on MRI are 39% (11/28) and 89% (24/27) and at least 2.5 mm on MR arthrography are 46% (6/13) and 85% (11/13). The sensitivity and specificity of high signal posterior to the biceps are 54% (15/28) and 74% (20/27) on MRI and 69% (9/13) and 54% (7/13) on MR arthrography. Increased width of high signal has a moderate specificity but a poor positive predictive value for distinguishing a SLAP tear from a normal recess. In addition, labral signal posterior to the biceps tendon is not rare in patients with no SLAP tear.