ePoster #804 - ISHA Annual Scientific Meeting 2016

Quantitative Magnetic Resonance Arthrography in Patients with Femoroacetabular Impingement

Alan L. Zhang, MD, San Francisco, CA UNITED STATES
Michael A. Samaan, PhD, San Francisco, CA UNITED STATES
Matthew C. Gallo, BA, San Francisco, CA UNITED STATES
Benedikt J. Schwaiger, MD, San Francisco, CA UNITED STATES
Thomas M. Link, MD, PhD, San Francisco, CA UNITED STATES
Richard B. Souza, PT, PhD, San Francisco, CA UNITED STATES
Sharmila L. Majumdar, PhD, San Francisco, CA UNITED STATES

University of California, San Francisco Medical Center, San Francisco, California, UNITED STATES

FDA Status Not Applicable

Summary: Quantitative MR sequences such as T1rho and T2 mapping have the ability to identify early articular cartilage injury in regions of impingement on the femoral head and acetabulum of FAI patients. The application of these sequences during MR arthrography of the hip may allow for earlier detection of damage to articular cartilage in addition to detailed assessment of labral pathology.

Abstract:
Background MR arthrography (MRA) of the hip can be used in patients with femoroacetabular impingement (FAI) for detailed assessment of labral pathology and localization of an intra-articular source for pain. However, standard MR sequences even when enhanced by intra-articular contrast have limited ability to identify articular cartilage injuries until significant cartilage loss or delamination has occurred. Quantitative magnetic resonance imaging (QMRI) sequences including T1rho and T2 mapping have been shown to detect early cartilage damage in the hip through changes in the proteoglycan and collagen content of articular cartilage. However, these quantitative sequences have not been utilized during MRA of the hip for evaluation of nascent articular cartilage injuries from FAI. Purpose The purpose of this study is to evaluate the use of T1rho and T2 mapping during MRA in FAI patients for assessment of early articular cartilage injury. Methods Ten patients with clinical and radiographic signs of FAI were evaluated using both MRI and MRA on their symptomatic hip. The scans were analyzed by fellowship-trained musculoskeletal radiologists and articular cartilage layers were segmented for quantitative analysis. Both global and sub-regional T1rho and T2 relaxation times of the acetabular and femoral articular cartilage were computed in the MRI and MRA assessments to evaluate cartilage matrix content. Agreement of T1rho and T2 relaxation times in the MRI and MRA sequences were assessed using the Krippendorff’s alpha coefficient and linear regression. Results In six male and four female patients (mean age 35) with symptomatic FAI, QMRI/QMRA sequences demonstrated elevated T1rho and T2 relaxation times in the anterior-superior region of the femoral head as well as the anterior-superior region of the acetabulum near the chondrolabral junction (indicating early cartilage injury in these regions). The average global and sub-regional T1rho and T2 relaxation times in the acetabular and femoral cartilage layers were similar for both the MRA and MRI scans. Overall, the Krippendorff alpha values for the acetabular and femoral cartilage layers ranged from 0.83 – 0.97 and demonstrated good agreement between the MRA and MRI values of T1rho and T2 relaxation times. The results of the linear regression produced estimated slopes of 0.85 – 0.97 and provided more evidence of strong agreement in quantitative cartilage assessment between MRA and MRI examinations. Conclusion Quantitative MR sequences such as T1rho and T2 mapping have the ability to identify early articular cartilage injury in regions of impingement on the femoral head and acetabulum of FAI patients. The application of these sequences during MR arthrography of the hip may allow for earlier detection of damage to articular cartilage in addition to detailed assessment of labral pathology.