Avacular Necrosis of the Femoral Head: MR Imaging with Histologic Correlation

ABSTRACT

PURPOSE: To correlate MR findings with histologic findings in avascular necrosis(AVN) of the femoral head. MATERIALS AND METHODS: MR imaging was performed with 8 femoral head specimens using T1- and proton density weighted coronal SE sequences, and compared with contact radiography and histologic sections. RESULTS: In each specimen, necrotic zone in the superior portion of femoral head, repair zone located inferior to the necrotic zone, and rim adjacent to normal bone marrow could be defined. Necrotic zone showed high signal intensity on both T1- and proton density- weighted images in 3 cases which were composed of necrotic bone and marrow, and low signal intensity on both sequences in 2 cases which were composed of necrotic bone marrow with amorphous cellular debris. Mixed high and low signal intensities were seen in 3 cases. The repair zone showed low signal intensity on Tl-weighted image and high signal intenisty on proton density weighted image in 5 cases which were composed of thickened trabecular bone and meSenchymal tissue and also showed intermediate signal intensity on T1 weighted image and high signal intensity on proton density weighted image in 3 cases which were composed of osteoid, chondroid and undifferentiated mesenchymal cells. Rim shown as the low signal intensity on T1 weighted image in all cases was corresponded to viable thickened trabecular bone. CONCLUSION: MR imaging would be the best modality in the diagnosis of avascular necrosis of fernoral head and when used in conjuction with degree and location of signal intensity, the prediction of histologic finding may be possible.