ePoster #809 - ISHA Annual Scientific Meeting 2016

Imaging Of Hip Articular Cartilage And Acetabular Labrum With Novel Oblique Mri Sequences

Albert Lu, MD, San Francisco, CA UNITED STATES
Thomas G. Sampson, MD, San Francisco, CA UNITED STATES
David Stoller, MD, San Francisco UNITED STATES

Radnet Medical Imaging, San Francisco, CA, UNITED STATES

FDA Status Not Applicable

Summary: Additional articular cartilage and labral pathologies were identified in arthroscopic zone 2 and zone 4 using novel oblique proton density fat sat images, compared with conventional coronal proton fat sat images.

Abstract:
Introduction: Accurate MRI imaging of hip articular cartilage and acetabular labrum has long been a challenging proposition due to relatively thin articular cartilage in the hip and its spherical geometry. Conventional coronal MR sequences provide only 1-2 slices of optimized visualization of cartilage and labrum without loss of resolution, namely at zone 3, where the scan plane is perpendicular to the curved acetabular roof. To better evaluate articular cartilage and labrum corresponding to arthroscopic zones 2 and 4, we developed novel anterior and posterior oblique proton density fat sat (PDFS) sequences to allow imaging planes perpendicular to anterosuperior and posterosuperior cycloid curvatures of the acetabular roof. Methods: 41 consecutive MRI scans using our new protocol that included anterior oblique and posterior oblique PDFS sequences were evaluated. 13 of the 41 cases were excluded due to prior hip surgery. In remaining 28 cases, the standard coronal PDFS sequences were compared with the anterior oblique PDFS sequence for evaluation of zone 2 pathology. Standard coronal PDFS sequences were also compared with posterior oblique PDFS sequences for evaluation of zone 4 pathology. MRI interpretation was performed by consensus reading of a musculoskeletal radiology fellow and a musculoskeletal radiologist with over 20 years of experience. Results: Of the 28 MRI studies, the anterior oblique sequence showed 5 cases of cartilage delamination in zone 2 not evident on conventional coronal sequence. In addition, there were two additional cases where the standard coronal image underestimated the degree of chondral loss. The anterior oblique did not demonstrate any additional labral pathology compared with the standard coronal sequence. There was one case in which a suspected anterosuperior labral tear seen on standard coronal image was shown to be artifactual in the anterior oblique sequence. The posterior oblique sequence demonstrated 3 cases of cartilage delamination in zone 4 that were not evident on conventional coronal sequence. There were also 4 cases in which the posterior oblique showed grade 3-4 cartilage loss in zone 4 that were completely not seen on the standard coronal sequence. The posterior oblique sequence also showed 2 posterior-superior labral tears not evident on the standard coronal sequence. Additonally, anterior oblique images improved conspicuity of femoral head/neck asphericity, improved visualization of ligamentum teres, and displayed the full course of the iliopsoas tendon on 1-2 images. Conclusion: Anterior oblique and posterior oblique PDFS sequences as additional imaging planes potentially improves the detection of chondral pathology in zone 2 and zone 4, respectively, and may improve the sensitivity and specificity of detection of labral tears in the anterosuperior and posterosuperior acetabulum.