Evaluation of cartilage matrix disorders by T2 relaxation time in patients with hip dysplasia

Early detection of cartilage disorder in dysplastic hips is important in predicting subsequent progression of osteoarthritis and determining the appropriate timing of osteotomy surgery. We assessed the feasibility of T2 assessment using magnetic resonance (MR) imaging at 3T for evaluating early changes in the acetabular and femoral cartilages for patients with hip dysplasia.

Sagittal T2 maps of the hip were obtained using 3T MR imaging in 10 normal volunteers (14 hips) and in 23 patients (26 hips) with hip dysplasia at pre-arthritic stage (without osteoarthritis) or early-arthritic stage (with osteoarthritis at the Kellgren-Lawrence system of grade 1 or 2). T2 values and the visual appearance of T2 mapping, including gradient T2, low T2, and high T2 patterns, were compared at the superior zones of the acetabular and femoral cartilages among the normal, pre-arthritic, and early-arthritic groups.

There were no significant differences in T2 values for both cartilages among the three groups. Regarding the visual appearance of T2 mapping for the acetabular cartilage, all hips in the normal group showed a gradient T2 pattern, while the pre-arthritic groups included six hips (43%) with a low T2 pattern, and the early-arthritic group showed either a low T2 pattern (33%) or a high T2 pattern (67%). The frequency of the gradient T2 pattern was significantly lower for dysplastic hips than for normal hips, in the acetabular and femoral cartilages (P<0.05).

This preliminary study demonstrated the clinical feasibility of T2 assessment of hip cartilage using 3T MR imaging. T2 mapping classification may enable the early detection of osteoarthritic degeneration and the detection of developmental disorders of cartilage matrix in patients with hip dysplasia.