Bone Marrow Avascular In Early Stage Of Traumatic Osteonecrosis Of Long Bone: Detection In Animal Models With MRI T₂mapping

Objective:To investigate and to detect the magnetic resonance imaging(MRI) T2mapping changes in rabbits bone marrow avascular in early stage of traumatic osteonecrosis.Methods:The left common iliac arterys of thirty-four New Zealand rabbits were occluded exclusively to create avascular osteonecrosis models. The right posterior limbs were selected as the control group. Before and after ischemia, the femurs of rabbits were scaned with T1WI, fat-suppression T2WI and T2mapping in axial plain per hour and the T2 values were measured. The femurs were pathologically examined. The T2 values were compared within and between groups and were investigated the coherent variation trend with time.Results:The avascular osteonecrosis models of the left femurs were established successfully. No significant changes were observed on T1WI and T2WI-fs. The T2 values results were shown as follow:①The means of normal T2 values was 52.75±2.64ms;②After ischemia, the T2 values of left side were lower than the control group, and the difference was statistically significant (P<0.05);③ompared with the T2 values before ligation, the left T2 values descended statistically significant (1h,2h,P=0.001; 3～6h,P=0.000; 7h,P=0.001);④The T2 values of left side performed a linear relation with the time(F=13.267, P=0.002<0.05), which was significantly different from the right control group(F=4.540, P=0.046<0.05).Conclusion:The T2 values are more sensitive than the normal MRI sequences, which facilitate the early diagnosis of osteonecrosis.