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合适的MRI检查序列可以显示兔的椎体和椎间盘病变[13]。正常椎体中脂肪成分较多,水含量较少,在SE序列T1WI图像上信号较高,T2WI信号稍高或等信号。实验组术后第3周,由于平阳霉素对椎体内微血管及血窦的破坏,软骨终板侧椎体缺血后呈无菌性的炎性和水肿反应,骨细胞和基质的缺血后反应也导致局部的水分含量增多;故在T1WI图像上信号降低,T2WI信号升高,尤其在T2加权脂肪抑制序列上椎体中脂肪组织高信号被抑制后,水含量增加引起T2驰豫时间延长,病变椎体组织信号强度会明显高于正常椎体组织,在MR图像上呈现出鲜明对比。本研究通过对实验组第4周T2WI高信号区面积(ST2WI)与病理切片病变区面积(Shistology)的相关性分析,显示两者间存在明显的正相关性(r = 0.965,P < 0.001),因此,MRI对软骨终板侧椎体缺血的诊断可信度较高,尤其T2WI及脂肪抑制T2WI有较高的诊断特异性和敏感性。
本实验通过穿刺终板侧椎体注入平阳霉素,破坏椎体血供诱发腰椎终板及椎间盘退变,不直接损伤软骨终板或椎间盘,比较接近椎间盘的自然退变病程。但是,就如何利用更加合适的MRI扫描序列更清晰显示终板及椎间盘退变过程。增加实验的样本量和更长的观察时间这些问题,还需在以后的实验中进一步完善。
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