Philip A. Dinauer MD, Presenter: Nothing to Disclose

John F. Carroll MD, Abstract Co-Author: Nothing to Disclose

Kevin Paul Murphy MD, Abstract Co-Author: Nothing to Disclose

To conduct a retrospective review of MR arthrography examinations in surgically confirmed cases of acetabular labral tear to determine which imaging plane is most sensitive to acetabular labral injury.

After obtaining institutional review board approval, two musculoskeletal radiologists retrospectively reviewed a total of 56 hip MR arthrography examinations with surgical correlation from a five year period (January 1999 through February 2004). All studies were obtained on a 1.5 Tesla magnet with a torso phased array coil. Intra-articular contrast consisted of either saline (n = 13) or dilute gadolinium (n = 43), field of view was 16 - 20 cm, slice thickness 3 - 4 mm, and matrix was 256 x 224 (or 192), with 2-4 acquisitions. Each MR study was performed in three planes: axial, sagittal-oblique, and coronal-oblique. The oblique images were acquired perpendicular to the orientation of the acetabular cup. Each study contained fat-saturated T1-weighted (TR 450 - 800 msec/TE 15 - 20 msec) and/or fast-spin-echo intermediate weighted sequences (TR 2000 - 3500 msec/TE 20 - 50 msec). Each imaging plane was reviewed for its ability to show the presence of an acetabular labral tear, defined as abnormal signal extending to the articular surface or base of the labrum. The radiologists, who were aware of surgical results, reached agreement by consensus. Preoperative MR reports were also reviewed.

Acetabular labral tears were detected by arthroscopic surgery in 52 of the 56 patients. All 52 patients had labral injury at either the anterior or anterosuperior acetabulum, and two patients had additional tearing at the posterior labrum. With MR arthrography, labral tears were identified preoperatively in 50 of 52 patients (96.1%), and these 50 labral injuries were also identified during retrospective consensus review. In 52 patients with labral injury, 88% of tears were visualized on sagittal-oblique images, compared to 48% on axial and 40% on coronal-oblique images.

The sagittal-oblique scanning technique has the greatest diagnostic value in hip MR arthrography. The vast majority of acetabular labral tears, located anteriorly or anterosuperiorly, can be visualized on these images.

Dinauer, P, Carroll, J, Murphy, K, MR Arthrography of Acetabular Labral Tears: Which Imaging Plane Best Depicts Labral Injury?.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4415523.html