MR Imaging of SLAP Lesions.

Robert D Boutin,Richard A Marder

doi:10.2174/1874325001812010314

Abstract

Background:SLAP lesions of the shoulder are challenging to diagnose by clinical means alone. Interpretation of MR images requires knowledge of the normal appearance of the labrum, its anatomical variants, and the characteristic patterns of SLAP lesions. In general, high signal extending anterior and posterior to the biceps anchor is the hallmark of SLAP lesions. Common diagnostic criteria for a SLAP lesion by MR or MR arthrography include the following: presence of a laterally curved, high signal intensity in the labrum on a coronal image, multiple or branching lines of high signal intensity in the superior labrum on a coronal image, full-thickness detachment with irregularly marginated high signal intensity and/or separation >2 mm on conventional MRI or 3 mm on MR arthrography between the labrum and glenoid on a coronal image, and a paralabral cyst extending from the superior labrum.Methods:MR diagnosis of SLAP tears may be improved with provocative maneuvers, such as longitudinal traction of the arm or positioning of the shoulder in abduction and external rotation during imaging. The use of intra-articular contrast distends the joint similar to what occurs during arthroscopy and forced diffusion under the labrum may improve the ability to detect SLAP lesions that might not be seen with standard MR. Improved diagnostic accuracy for SLAP tears is seen with 3-T compared with 1.5-T MR imaging, with or without intra-articular contrast material.Conclusion:Regardless of MR findings, however, physicians should be cautious when recommending surgery in the patient with a vague clinical picture. The patient’s history, physical exam, and imaging evaluation all should be considered together in making the decision to proceed with surgery.

Highlights

SLAP lesions of the shoulder are challenging to diagnose by clinical means alone [1]
Diagnostic criteria for a SLAP lesion by MR or MR arthrography most commonly include the following [29, 33]: 1. laterally curved, linear signal in the labrum on coronal imaging (Fig. 5); 2. multiple or branching lines of high signal intensity in the superior labrum on coronal imaging (Fig. 6); 3. full-thickness detachment with irregularly marginated high signal intensity and/or wide separation between the labrum and glenoid on coronal imaging (Fig. 7); 4. a paralabral cyst extending from the superior labrum [34] (Fig. 8)
There is some evidence that the MR diagnosis of SLAP tears may be improved with provocative maneuvers, such as longitudinal traction of the arm [39] or positioning the shoulder in abduction and external rotation during imaging [40, 41]

Summary

Introduction

SLAP lesions of the shoulder are challenging to diagnose by clinical means alone [1]. Injury occurs from inferior traction on the shoulder, as well as excessive tension on and twisting of the Long Head of Biceps tendon (LHB) at its insertion along the superior labrum that occurs during the cocking motion of throwing [2, 3]. These mechanisms of injury are associated with a myriad of other shoulder conditions including rotator cuff tendinopathy, bicipital tendinopathy and subluxation, internal impingement, and glenohumeral instability. Specialized exam tests have been developed that help the LHB insertion to assist in the clinical diagnosis Common diagnostic criteria for a SLAP lesion by MR or MR arthrography include the following: presence of a laterally curved, high signal intensity in the labrum on a coronal image, multiple or branching lines of high signal intensity in the superior labrum on a coronal image, full-thickness detachment with irregularly marginated high signal intensity and/or separation >2 mm on conventional MRI or 3 mm on MR arthrography between the labrum and glenoid on a coronal image, and a paralabral cyst extending from the superior labrum

Methods

Findings

Discussion

Conclusion