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合適的MRI檢查序列可以顯示兔的椎體和椎間盤病變[13]。正常椎體中脂肪成分較多,水含量較少,在SE序列T1WI圖像上信號較高,T2WI信號稍高或等信號。實驗組術(shù)后第3周,由于平陽霉素對椎體內(nèi)微血管及血竇的破壞,軟骨終板側(cè)椎體缺血后呈無菌性的炎性和水腫反應,骨細胞和基質(zhì)的缺血后反應也導致局部的水分含量增多;故在T1WI圖像上信號降低,T2WI信號升高,尤其在T2加權(quán)脂肪抑制序列上椎體中脂肪組織高信號被抑制后,水含量增加引起T2馳豫時間延長,病變椎體組織信號強度會明顯高于正常椎體組織,在MR圖像上呈現(xiàn)出鮮明對比。本研究通過對實驗組第4周T2WI高信號區(qū)面積(ST2WI)與病理切片病變區(qū)面積(Shistology)的相關性分析,顯示兩者間存在明顯的正相關性(r = 0.965,P < 0.001),因此,MRI對軟骨終板側(cè)椎體缺血的診斷可信度較高,尤其T2WI及脂肪抑制T2WI有較高的診斷特異性和敏感性。
本實驗通過穿刺終板側(cè)椎體注入平陽霉素,破壞椎體血供誘發(fā)腰椎終板及椎間盤退變,不直接損傷軟骨終板或椎間盤,比較接近椎間盤的自然退變病程。但是,就如何利用更加合適的MRI掃描序列更清晰顯示終板及椎間盤退變過程。增加實驗的樣本量和更長的觀察時間這些問題,還需在以后的實驗中進一步完善。
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