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目的:探讨MR扩散系数值对急性脑梗死继发出血(HT)预测的价值。方法:75只兔颈内动脉注射自体血栓制作急性脑梗死模型,证实脑梗死的动物在3.0TMR设备上依次行3、6、12、24、48及72h扩散加权成像(DWI),获得表观扩散系数(ADC)图及指数扩散系数(EDC)图。采用欧洲急性中风合作研究方法(ECASS)对病理证实的HT进行分型,包括无HT组与HT组,后者又分为斑点状出血组(HI)及较大出血组(PH)。应用SPSS11.5统计学软件比较无HT组与不同程度HT组之间ADC及EDC值有无差异。结果:59只(78.67%)动物模型制作成功,其中无HT组21只(35.59%,21/59)、HI组31只(52.54%,31/59)、PH组7只(11.87%,7/59)。无HT组3～72h梗死区ADC值为(0.601±0.128)×10-3～(0.813±0.060)×10-3,HT组ADC值为(0.432±0.091)×10-3～(0.618±0.060)×10-3,各时间点两组ADC值差异均有统计学意义(t值为2.417～5.986,P值为0.000～0.031)。无HT组3～72h梗死区EDC值为(0.415±0.039)～(0.502±0.009),HT组EDC值为(0.559±0.040)～(0.583±0.064),两组各时间点EDC值差异均有统计学意义(t值为4.002～6.995,P值为0.000～0.002)。HI组3～72h梗死区ADC值为(0.435±0.091)×10-3～(0.631±0.045)×10-3,PH组ADC值为(0.390±0.180)×10-3～(0.586±0.104)×10-3,除24h(t值为4.664,P=0.002)外,其余时间点HI组与PH组ADC值均无统计学差异(t值为0.057～1.996,P值为0.171～0.956)。HI组3～72h梗死区EDC值为(0.545±0.039)～(0.638±0.042),PH组EDC为(0.575±0.054)～(0.649±0.019),各时间点两组间EDC值无明显统计学差异(t值为0.051～1.698,P值0.150～0.960)。结论:脑梗死急性期ADC值及EDC值变化与HT的发生存在着相关性,ADC值下降及EDC值增高有可能预测HT的出现,但仅根据扩散系数值不能预测HT的程度。
Objective: To investigate the value of MR diffusion coefficient in prediction of secondary hemorrhage (HT) in acute cerebral infarction. Methods: Thirty-six rabbits received autologous thrombus injection through the internal carotid artery to establish a model of acute cerebral infarction. Confirming cerebral infarction animals were subjected to diffusion-weighted imaging (DWI) at 3.0, 6, Diffusion coefficient (ADC) and exponential diffusion coefficient (EDC). Histopathologically confirmed HT were classified using the European Cooperative Acute Stroke Study (ECASS) model, including the HT-free and HT-free groups, which were divided into a haemorrhagic (HI) and a hemorrhagic (PH) group. SPSS11.5 statistical software was used to compare the difference of ADC and EDC between HT group and HT group. Results: Fifty-one (78.67%) animals were successfully established. Among them, 21 animals in the HT group (35.59%, 21/59), 31 animals in the HI group (52.54%, 31/59) and 7 animals (11.87%, 7 / 59). The ADC value of infarction zone in 3 ~ 72 h group without HT group was (0.601 ± 0.128) × 10-3 ~ (0.813 ± 0.060) × 10-3, and the ADC value in HT group was (0.432 ± 0.091) × 10-3 ~ (0.618 ± 0.060 ) × 10-3. There was significant difference in ADC value between the two groups at each time point (t = 2.417-5.986, P = 0.000-0.031). The EDC values in the non-HT group ranged from (0.415 ± 0.039) to (0.502 ± 0.009) in the infarct zone at 3 ~ 72 h and that in the HT group was (0.559 ± 0.040) ~ (0.583 ± 0.064) Statistical significance (t value of 4.002 ~ 6.995, P value of 0.000 ~ 0.002). The ADC value of infarction area at 3-72h in HI group was (0.435 ± 0.091) × 10-3 ~ (0.631 ± 0.045) × 10-3, and that in PH group was (0.390 ± 0.180) × 10-3 ~ (0.586 ± 0.104) × 10-3, except for 24h (t = 4.664, P = 0.002), there was no significant difference in ADC values between the HI and PH groups at other time points (t = 0.057-1.996, P = 0.171-0.956). The EDC value of infarction area in HI group was (0.545 ± 0.039) ~ (0.638 ± 0.042) at 3 ~ 72h and that of PH group was (0.575 ± 0.054) ~ (0.649 ± 0.019), there was no significant difference in EDC between two groups Differences (t = 0.051-1.698, P = 0.150-0.960). CONCLUSION: The changes of ADC value and EDC value in acute stage of cerebral infarction are related to the occurrence of HT. The decrease of ADC value and the increase of EDC value may predict the occurrence of HT, but the degree of HT can not be predicted only based on the value of diffusion coefficient.