【摘要】 目的:研究动态和延迟增强MRI诊断乳猪早期股骨头骨骺软骨缺血的价值。材料和方法:24例2~3周龄乳猪随机分为正常组10例,缺血组14例。缺血模型制作采用双髋关节蛙式位固定1h~12h,MRI扫描序列包括SET1WI、FSET2WI、动态和延迟增强MRI扫描。扫描完成后解除固定,并于1d和1周后行MRI复查。采用时间-信号强度曲线观察股骨头骨骺二次骨化中心首过灌注状态并测量相对强化比率,采用延迟增强MRI信号变化观察骨骺软骨的造影剂弥散情况,并与组织学检查行对照研究。结果:正常组10例双侧股骨头骨骺二次骨化中心动态增强扫描呈早期快速强化,相对强化比率平均值为1.51±0.46。延迟扫描骨骺软骨强化均匀。缺血组14例,固定3h和6h者各5例,固定1h和12h者各2例。14例共28个股骨头中,MRI平扫均未见异常。动态MRI增强扫描显示24个股骨头骨骺二次骨化中心呈低灌注状态,相对强化比率平均值为0.34±0.13,与正常组比较有显著统计学差异。延迟MRI扫描20个股骨头骨骺呈片状不强化或强化减低区。其中,4个股骨头可见灌注异常而延迟增强MRI扫描呈正常强化。1d后复查,13个股骨头恢复正常强化,另7个股骨头1周后复查也恢复正常强化。组织学检查显示所有28个股骨头骨骺均未见缺血坏死征象。结论:动态MRI增强扫描能敏感地发现乳猪蛙式位固定后股骨头骨骺二次骨化中心的早期缺血性改变,延迟增强MRI能很好地显示骨骺软骨的缺血,两者结合使用能较好地评价股骨头骨骺软骨早期缺血及其恢复。更多还原

【Abstract】 To study dynamic and delayed Gadolinium-enhanced MRI in the early diagnosis of ischemia demage of the capital femoral cartilage in piglets. Materials and Methods:Twenty-four 2-to 3-week-old piglets were divided into 2 groups randomly, including normal group(n=10) and ischemia group(n=14). The piglets in the ischemia group had been placed in maximal bilateral hip abduction for 1 to 12 hours. MRI sequences included SE T1WI、FSE T2WI、dynamic contrast-enhanced MRI(dynMRI) and delayed gadolinium-enhanced MRI (dGEMRI). After MRI study, the piglets were allowed to ambulate freely for 1 or 7 days and re-imaged. Initial perfusion was studied by drawing time-intensity curves and relative enhancement ratio was measured. Diffusion of gadolinium into the cartilaginous epiphyses was evaluated with delayed enhanced-MRI and comparison between MRI appearances and histologic findings was made. Results: DynMRI demonstrated early and fast enhancement of the capital femoral epiphysis in normal piglets and dGEMRI showed homogeneous enhancement in cartilaginous epiphyses. The relative enhancement ratio was 1.51±0.46. In the ischemia group, there were respectively five piglets placed in hip hyperabduction for 3 and 6 hours and two for 1 and 12 hours. On SE T1WI and FSE T2WI, no abnormal sign was found in all twenty-eight femoral head of 14 piglets. dynMRI showed decreased perfusion in 24 femoral heads of all 28 femoral head after maximal hip abduction and the relative enhancement ratio was 0.34±0.13. The relative enhancement ratio of the ischemia group had statistic difference with that of the normal group. On delayed Gd-enhanced MRI, decreased or absent enhancement was seen in 20 cartilaginous epiphyses of all 28 femoral heads. Four femoral head showed decreased initial perfusion but normal delayed enhancement. Reperfusion was completed in 13 of the 20 femoral heads after one day of ambulation and in the rest 7 femoral heads after seven days of ambulation. There was no necrosis in epiphyses founded on histology examination. Conclusion:dynMRI can detect early ischemia of 2nd ossification center in the capital femoral epiphysis and dGEMRI can revealed the ischemia of the epiphseal cartilage. The binding of two MRI techniques should benefit the early diagnosis of the ischemia with the capital femoral epiphysis in piglets by hip hyperabdudion and its reversal.更多还原