Lesions of the acetabular labrum: accuracy of MR imaging and MR arthrography in detection and staging.

Abstract

To determine the accuracy of magnetic resonance (MR) imaging and MR arthrography in the detection and staging of lesions of the acetabular labrum. Fifty-seven hips of 56 patients with chronic hip pain and a strong clinical suspicion of labral lesions were examined with a three-dimensional gradient-echo sequence in the coronal oblique and sagittal oblique projections before and after the intraarticular injection of gadopentetate dimeglumine. The labra were evaluated on the basis of morphology, signal intensity, the presence or absence of a tear, and their attachment to the acetabulum. Twenty-two of the hips underwent surgical intervention, and 35 hips were treated conservatively. Twenty of the 22 labra with surgical proof were staged accurately with MR arthrography. On the conventional MR images, only eight of the 22 labra were staged correctly. Whereas the sensitivity of MR arthrography was 90% and its accuracy was 91%, the sensitivity of MR imaging was 30% and its accuracy was 36%, compared with surgical findings. MR arthrography enables accurate detection and staging of lesions of the acetabular labrum and appears to be indicated in the assessment of chronic hip pain in patients with a strong suspicion of labral lesions.