Femoral head perfusion and composition: MR imaging and spectroscopic evaluation of patients with systemic lupus erythematosus and at risk for avascular necrosis

PURPOSE: To measure fat content and relative marrow perfusion of the femoral head in patients at risk for avascular necrosis. MATERIALS AND METHODS: Thirteen patients with systemic lupus erythematosus (SLE) without avascular necrosis and with long-term corticosteroid treatment and 12 healthy subjects were evaluated. Hip perfusion was assessed with gadolinium-enhanced T1-weighted magnetic resonance (MR) imaging. Marrow composition in the femoral head and neck was measured with hydrogen-1 MR spectroscopy. RESULTS: Percentage fat content in the femoral head was similar between the two groups (SLE patients, 77% ± 5 [standard deviation]; healthy subjects, 78% ± 6; P = .74). Rate of enhancement of the femoral head was significantly higher in the SLE than the healthy group (11%/min ± 6 vs 6.9%/min ± 3, respectively; P = .05), was inversely related to fat content in healthy subjects (r = -.74, P = .02), and was more variable in the SLE group (r = -.53, P = .11). CONCLUSION: Perfusion of the femoral head is inversely related to marrow fat content in healthy subjects and is higher in SLE patients without hip avascular necrosis.