Avascular Necrosis of Femoral Head: Findings of Contrast-Enhanced MR Imaging

PURPOSE: To evaluate the findings and the role of contrast enhanced magnetic resonance imaging in avascular necrosis of femoral head. MATERIALS AND METHODS: Sixteen patients with avascular necrosis of femoral head were examined with MRI. Tl-weighted and T2-weighted images and contrast-enhanced Tl-weighted images were obtained. Enhancing characteristics of the necrotic area and synovium were determined. Also a change of the disease extent after enhancement was assessed. RESULTS: Twenty seven avascular necrosis of the femoral head including 11 cases of bilateral lesion were detected. Fifteen cases revealed collapse of the femoral head. The portions of the lesion with low signal intensity on Tl-weighted images and high signal intensity on T2-weighted images showed contrast enhancement in 15 cases. However, the portions with low signal intensities both on T1 and T2-weighted images showed enhancement in one case. There was no significant change of the disease extent after enhancement. Synovium showed enhancement in 18 cases, and joint effusion was detected in 23 cases. CONCLUSION: Contrast enhanced MR images may be helpful in predicting histopathologic findings of avascular necrosis of the femoral head, but not useful for evaluating the extent of disease.