Early Detection of Steroid-Induced Femoral Head Necrosis using 99mTc-Cys-Annexin V-based Apoptosis Imaging in a Rabbit Model

Abstract Background At present, the early diagnosis of femoral head necrosis mainly relies on MRI, and most early patients are difficult to make an accurate diagnosis. Therefore, to investigate the early diagnostic value of 99mTc-Cys-Annexin V SPECT imaging were compared with MRI in rabbit models of steroid-induced femoral head necrosis. Methods The rabbit models of steroid-induced femoral head necrosis were established by intravenous injection of horse serum and gluteal muscle injection of methylprednisolone in of 5-month-old healthy New Zealand white rabbits. 99mTc-Cys-Annexin V SPECT imaging and MRI were performed at 2nd week, 4th week, and 6th week after modeling. After that, histopathology was used to verify the success of modeling. Apoptosis was detected by transmission electron microscopy and TUNEL. Results At 2 weeks after the injection of hormone, 99mTc-Cys-Annexin V SPECT image showed abnormal radioactive uptake in the bilateral femoral head. And over time, the radioactivity concentration was more obvious, and the ratio of T/NT (target tissue/non-target tissues) was gradually increased. In the SPECT imaging at each time point, T/NT ratio of the model group was significantly higher than that of the control group (P < 0.01); at 4 weeks after the injection of hormone, MRI showed an abnormal signal of osteonecrosis. At 2, 4, and 6 weeks after hormone injection, apoptosis was observed by TUNEL and transmission electron microscopy. Conclusions 99mTc-Cys-Annexin V SPECT imaging can diagnose steroid-induced femoral head necrosis earlier than MRI, and has potential application value for non-invasively detecting early and even ultra-early stage of femoral head necrosis.