The Role of99mTc-Annexin V Apoptosis Scintigraphy in Visualizing Early Stage Glucocorticoid-Induced Femoral Head Osteonecrosis in the Rabbit
Objective. To validate the ability of99mTc-Annexin V to visualize early stage of glucocorticoid-induced femoral head necrosis by comparing with99mTc-MDP bone scanning.Methods. Femoral head necrosis was induced in adult New Zealand white rabbits by intramuscular injection of methylprednisolone.99mTc-Annexin scintigraphy and99mTc-MDP scans were performed before and 5, 6, and 8 weeks after methylprednisolone administration. Rabbits were sacrificed at various time points and conducted for TUNEL and H&E staining.Results. All methylprednisolone treated animals developed femoral head necrosis; at 8 weeks postinjection, destruction of bone structure was evident in H&E staining, and apoptosis was confirmed by the TUNEL assay. This was matched by99mTc-Annexin V images, which showed a significant increase in signal over baseline. Serial99mTc-Annexin V scans revealed that increased99mTc-Annexin V uptake could be observed in 5 weeks. In contrast, there was no effect on99mTc-MDP signal until 8 weeks. The TUNEL assay revealed that bone cell apoptosis occurred at 5 weeks.Conclusion.99mTc-Annexin V is superior to99mTc-MDP for the early detection of glucocorticoid-induced femoral head necrosis in the rabbit and may be a better strategy for the early detection of glucocorticoid-induced femoral head necrosis in patients.