Serial magnetic resonance imaging in a non-traumatic rabbit osteonecrosis model: an experimental longitudinal study

We investigated the time-dependent natural course of experimental osteonecr osis (ON), including initial changes in ON and the reparative process, usin g in vivo serial repetitive magnetic resonance imaging (MRI) in a non-traum atic rabbit serum sickness ON model. Some necrotic lesions were detected at 1 week (3 of 16 femora with necrotic lesions) and some in the metaphysis w ere detected by 12 weeks (2 of 6 femora with lesions) on T-1-weighted. T-2- weighted, and far suppression T-1-weighted images. On contrast-enhanced MRI , extravasation of the erythrocytes was detected at 72 h (7 of 26 femora wi th lesions) as a small, focal enhanced area. Necrotic lesions were detected in all abnormal femora by 6 weeks (16 of 16 femora with lesions) as focal, homogeneously or inhomogeneously enhanced areas. Reparative tissue replace d with new vascular and trabecular formation in necrotic areas was detected as an extended marginal enhanced area at 12 weeks. These results suggest t hat the enhancement patterns on contrast-enhanced MRI may provide helpful i nformation about the developmental and reparative process of clinical ON. ( C) 2000 Elsevier Science Inc. All rights reserved.