MR measurement of articular cartilage thickness distribution in the hip

Objective: To develop a method to determine the distribution of articular cartilage in the hip and to evaluate the potential of the method in a study of normal weight-bearing effects in asymptomatic young volunteers. Design: Six volunteers were scanned after periods of standing and lying supine, using 3D gradient-echo magnetic resonance imaging (MRI). The protocol was repeated for two successive weeks to determine reproducibility. The femoral and acetabular cartilage layers were segmented as a single unit and thickness distribution maps were calculated using a spherical bone model as a frame of reference. Thickness maps were combined over the population using the bone model and post-weight-bearing and post-resting maps were compared. Results: Mean thickness values were compared using an analysis of variance and a significant increase in cartilage thickness of 0.05 mm (P=0.02) was observed. The reproducibility of the method, assessed using test-retest coefficient of variation was 2.5%. Conclusions: The technique is reproducible, sensitive to sub-millimetre changes in thickness and may be useful in monitoring changes due to disease progression in patients with arthritis of the hip. (C) 2006 OsteoArthritis Research Society International. Published by Elsevier Ltd. All rights reserved.