目的 利用MR扩散张量成像(DTI)观察兔轻度脑挫裂伤(CCL)的扩散特征及病理改变.方法 40只新西兰大白兔随机抽取30只行自由落体制作轻度CCL模型,另10只仅切开局部颅骨作为对照组.术后1、3、6、12、24、48及72 h行T2WI与DTI,以1 h MRI为基准,测量和比较各时间点CCL区及其周边区的DTI参数.病理学观察CCL区与周边区组织学表现. 结果 1 h时间点CCL区T2WI为高信号,周边区无明显异常信号,但在DTI各参数图上均呈异常色阶.22只兔(73.33%)3 h后周边区T2WI逐渐增高,T2WT示踪图异常色阶更明显.各时间点CCL区和周边区与镜像区FA和Dcavg值间差异均有统计学意义(P<0.05),各时间点CCL与周边区FA值12 h以后均轻微下降.病理学上CCL区组织坏死、水肿及出血均较周边区明显.对照组病理学及MR检查脑组织未见异常. 结论 DTI能敏感地显示轻度CCL及其周边区的损伤性病变,并能以伪彩图方式显示;临床上应常规应用DTI评价轻度CCL.%Objective To observe the diffusion characteristics and pathology changes with DTI in rabbit models with mild cerebral contusion and laceration (CCL). Methods Thirty rabbits were randomly selected and made into models of mild CCL by free fall, while other 10 rabbits were cut only in the skull as control. T2WI and DTI were performed 1, 3, 6, 12, 24, 48 and 72 h after the operation. DTI value of average diffusion coefficient (DCavg) and fractional anisotropy (FA) of mild CCL and its peripheral area were measured and compared. Histological examination was also performed. Results One hour after operation, CCL area showed high signal on T2WI, and no abnormal signal was found in the peripheral area, but both had abnormal color on DTI map. T2WI signal intensity in peripheral area of 22 rabbits (73.33%) increased gradually and had much abnormal color on T2WT map after 3 h. There was significant difference of FA and DCavg between CCL and the mirror region, the peripheral area and the mirror region (P<0.05). The value of FA decreased slightly since 12 h. More prominent tissue necrosis, edema and hemorrhage were found in CCL area than in the peripheral area with pathology examination. No abnormal manifestations of the brain were detected with both pathology and MR examination in the control rabbits. Conclusion DTI is sensitive for detecting mild CCL and can show it directly on color map, and thus may be used as a routine examination in the evaluation of mild CCL.
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