3.0T MR DTI及T2mapping成像在兔急性缺血性横纹肌溶解症中的应用

发布时间：2018-09-01 17:24

【摘要】：目的：探讨急性缺血性横纹肌溶解症肌肉损伤在DTI及T2mapping成像上的影像学变化规律及相应病理基础；探讨DTI及T2mapping成像在评估急性缺血性横纹肌溶解症肌肉损伤中的价值；为临床应用DTI及T2mapping成像评估患者横纹肌溶解症病情提供实验参考。材料与方法：从32只新西兰大白兔中随机数字表法选取2只兔行建模前及建模后8小时DSA检查，证实本实验所采用的急性缺血性横纹肌溶解症模型的建立方法具有可行性。另30只兔随机数字表法分为5组(n=6)：A组为正常对照组；B组为缺血2小时观察组；C组为缺血4小时观察组；D组为缺血6小时观察组；E组为缺血8小时观察组。A、B、C、D组为时间点观察组，各组在相应观察时间点行磁共振检查、组织病理学检查及细胞凋亡检测，，但E组为磁共振检查连续观察组，行缺血前及缺血1~8小时，共行9次磁共振检查，动态观察兔左后肢缺血在磁共振成像上随时间变化的规律，9次磁共振检查完成后取组织行组织病理学检查及细胞凋亡检测。采用3.0T GE超导型磁共振扫描仪(Signa HDxt)，单通道包裹式表面线圈，扫描序列为轴位T2WI-FS、T1WI、DTI、T2mapping。在GE ADW4.4后处理工作站处理DTI及T2mapping数据，获得缺血前后左侧股直肌内侧部分ADC值、FA值、T2值及其纤维示踪图像。在左侧股直肌内侧部分取材行组织病理学检查(HE染色)及细胞凋亡检测(包括TUNEL染色计算细胞凋亡指数和Western blot检测活化的caspase-3蛋白的相对表达水平)。将影像学结果与组织病理结果及细胞凋亡结果相对照，研究急性缺血性横纹肌溶解症肌肉损伤的影像学变化规律。结果：T2WI-FS图像上可见，左侧股直肌内侧部分自缺血1小时开始出现进行性增高信号；T1WI图像上可见，缺血前后信号未见明显改变；纤维示踪图像上可见，随着缺血时间推移，肌纤维走行变得僵硬，部分肌纤维分离及移位；ADC值自缺血1小时开始出现进行性下降，缺血4小时下降至最低，缺血7小时ADC值开始出现缓慢升高趋势(P0.05)；FA值自缺血1小时开始出现进行性升高，缺血4小时达高峰，缺血7小时FA值开始出现缓慢下降趋势(P0.05)；T2值自缺血1小时开始出现进行性升高，缺血4小时达峰值，缺血6小时T2值开始出现缓慢下降趋势(P0.05)；HE染色见，D组缺血6小时出现颗粒变性，E组缺血8小时出现肌细胞溶解；ADC值、T2值改变与细胞凋亡指数改变呈中度相关，FA值与细胞凋亡指数改变呈低度相关；ADC值、FA值及T2值改变与活化的caspase-3蛋白的相对表达水平均呈中度相关。结论：1) ADC值、FA值和T2值能够及时、客观、准确量化反映缺血性横纹肌溶解症肌肉损伤从肌细胞水肿到肌细胞溶解的病理改变过程,纤维示踪成像能直观显示缺血肌肉肌纤维排列结构改变，DTI和T2mapping成像是评估横纹肌溶解症发生部位、程度及范围的较优无创检查方法。2)横纹肌溶解症急性期(8h)，肌肉损伤ADC值整体呈先下降后升高的趋势，FA值整体呈先升高后下降的趋势，T2值整体呈先升高后下降的趋势，纤维示踪可见肌纤维走行僵硬，部分肌纤维分离移位。3) T2WI-FS排除了脂肪组织干扰，是监测横纹肌溶解症损伤肌肉大体形态改变的较好序列。
[Abstract]:Objective: To investigate the imaging changes and pathological basis of acute ischemic rhabdomyolysis muscle injury on DTI and T2 mapping imaging, to explore the value of DTI and T2 mapping imaging in evaluating acute ischemic rhabdomyolysis muscle injury, and to evaluate the clinical application of DTI and T2 mapping imaging in patients with rhabdomyolysis. The disease provides experimental reference.
MATERIALS AND METHODS: Two rabbits were randomly selected from 32 New Zealand white rabbits for DSA examination before and 8 hours after modeling, which confirmed the feasibility of establishing acute ischemic rhabdomyolysis model. Blood 2-hour observation group; blood 4-hour observation group in group C; ischemia 6-hour observation group in group D; ischemia 8-hour observation group in group E; time point observation group in group A, B, C and D; magnetic resonance imaging, histopathological examination and apoptosis detection in each group at the corresponding observation time point, but magnetic resonance imaging continuous observation group in group E, before and after ischemia and deficiency. The changes of ischemia of left hind limb with time were dynamically observed by 9 magnetic resonance imaging (MR) in rabbits. After 9 MR examinations, the tissues were taken for histopathological examination and apoptosis detection. Axial T2WI-FS, T1WI, DTI, T2 mapping. DTI and T2 mapping data were processed at GE ADW4.4 post-processing workstation. ADC, FA, T2 values and fiber tracing images of the medial part of the left rectus femoris were obtained before and after ischemia. Histopathological examination (HE staining) and apoptosis detection (including TUNEL staining) were performed in the medial part of the left rectus femoris. Apoptosis index and Western blot were used to detect the relative expression level of activated caspase-3 protein.The imaging results were compared with histopathological results and apoptosis results to study the imaging changes of acute ischemic rhabdomyolysis muscle injury.
Results: On T2WI-FS images, the medial part of the left rectus femoris began to show progressive signal enhancement after 1 hour of ischemia; on T1WI images, the signal did not change significantly before and after ischemia; on fiber tracing images, muscle fibers became stiff, some muscle fibers were separated and displaced; ADC value was self-ischemic. The ADC value increased slowly at 7 hours after ischemia (P 0.05); the FA value increased progressively from 1 hour after ischemia, peaked at 4 hours after ischemia, and decreased slowly at 7 hours after ischemia (P 0.05); the T2 value increased progressively from 1 hour after ischemia. High, ischemia 4 hours peak, ischemia 6 hours T2 began to show a slow decline trend (P 0.05); HE staining showed that D group ischemia 6 hours granular degeneration, E group ischemia 8 hours myolysis; ADC value, T2 value and apoptosis index changes were moderately correlated, FA value and apoptosis index changes were low correlation; The expression of T2 and the relative expression level of activated caspase-3 protein were moderately correlated.
Conclusion: 1) ADC value, FA value and T2 value can reflect the pathological changes from myoedema to myolysis accurately and quantitatively in ischemic rhabdomyolysis. Fiber tracer imaging can visually show the changes of myofibrillar arrangement in ischemic muscle. DTI and T2 mapping imaging are used to evaluate the occurrence of rhabdomyolysis. 2) In the acute phase of rhabdomyolysis (8h), the ADC value of muscle injury decreased first and then increased, the FA value increased first and then decreased, the T2 value increased first and then decreased, and the fibers traced showed that the muscle fibers were stiff, and some of the muscle fibers were separated and displaced. 3) T2WI-FS Eliminating the interference of adipose tissue is a good sequence for monitoring the gross morphological changes of injured muscles in rhabdomyolysis.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R445.2;R685

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