Loaded Cartilage T2 Mapping in Patients with Hip Dysplasia

Abstract

To evaluate the change in cartilage T2 values with loading in patients with hip dysplasia. Fifteen patients with hip dysplasia and nine asymptomatic healthy volunteers were evaluated between April 2008 and February 2009. All subjects provided written informed consent before participation in this prospective, institutional review board-approved study. Midcoronal T2 mapping of hips was performed under unloaded and loaded conditions (with 50% body weight) at 3.0-T magnetic resonance (MR) imaging. Loading was achieved with a mechanical loading system. T2 values under unloaded conditions and the change in T2 values at the weight-bearing area of the acetabular and femoral cartilage with loading were compared between normal and dysplastic hips. The change in T2 with loading was correlated with the patient's age and body mass index as well as with the center-edge angle determined on conventional radiographs. The decrease in cartilage T2 at the outer superficial zones of the acetabular cartilage with loading was significantly greater in patients with hip dysplasia than in healthy volunteers: The mean T2 change with loading was -7.6% +/- 10.6 (+/-standard deviation) for dysplastic hips and 1.2% +/- 10.9 for normal hips (P = .04). Among patients with hip dysplasia, there was a positive correlation between the center-edge angle on anteroposterior radiographs and T2 changes with loading at the outer deep zones of the acetabular cartilage. Cartilage T2 mapping with loading during MR imaging enabled the detection of site-specific changes in cartilage T2 in dysplastic hips.