MR-arthrography of the acetabular larbrum - radiologic-pathologic correlation in 20 cadaveric hip joints.

Purpose: To investigate frequency of acetabular labral lesions in elderly h ip joints, and to determine sensitivity and specificity of MR arthrography (MRa) for the detection of these abnormalities. Materials and Methods: Twen ty cadaveric hip joints were examined by MRa. For MRa, 15 ml of a solution of iodinated contrast solution (Solutrast 300) and Gd-DTPA (100:1) were inj ected under fluoroscopic guidance. MR imaging was performed on a 1.5 T MR s canner (Vision, Siemens; FOV 16 cm, matrix 256 x 256, fat-suppressed 3D-FLA SH). Multiplanar image reconstructions were done perpendicular to the aceta bulum in the oblique-coronal, oblique-axial, and radial planes. The labral specimens were examined macroscopically. Results: In 12/20 hips (60%), a la bral lesion was found on pathologic examination. In 7 specimens, the labrum was partially or completely detached in the weight-bearing superior region . One flap-like variant of the labrum was seen; in 4 hip joints, the labrum was degenerated (one cystic degeneration). Pathologic findings were confir med by MRa in 8/12 specimens (sensitivity 67%). All degenerated labra were correctly diagnosed on MRa. Three small labral detachments and the flap-lik e variant were misinterpreted as being normal. There were no false positive findings (specificity 100%). The accuracy was 80%. Labral lesions were see n in 6/8 and in 6/12 of hips with and without osteoarthritis, respectively. Conclusion: MRa is well suited to delineate the acetabular labrum and to d iagnose labral abnormalities. Detection of small labral detachments and ana tomic variants is difficult and requires some experience. Labral lesions ar e correlated to osteoarthritis of the hip, but may be frequently seen in th e elderly without underlying osteoarthritis.