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目的:以磁共振扩散张量成像（DTI）为活体动态连续监测手段，分析轴突导向分子（RGMa）在缺血性脑梗死后大鼠脑组织核心梗死区及远隔脑区的表达变化与轴突再生、突触重塑及磁共振参数的关系，以及其在缺血性脑梗死的神经康复治疗及调控中的作用，并提供有效无创的影像学检查技术手段。方法:将SD大鼠72只随机分为对照组、大脑中动脉栓塞（MCAO）术后12 h、24 h、48 h、7 d、10 d组，每组大鼠12只。在相应时间点给予头部磁共振扫描后，测量各组大鼠梗死核心区、双侧小脑表观弥散系数（ADC）值和各向异性分数（FA）值。扫描后取各组大鼠相应部位脑组织分别行RT-PCR和免疫组化方法检测RGMa表达情况，采用免疫组化法检测各组大鼠轴突再生和突触重塑情况，并应用透射电镜观察各组大鼠细胞超微结构变化。采用Spearman相关分别分析大鼠脑梗死核心区和双侧小脑RGMa蛋白与神经微丝蛋白（NFP-200）、磁共振ADC值及FA值的相关性。结果:缺血性脑梗死后的各时间点大鼠梗死核心区和双侧小脑ADC值和FA值较对照组降低（均n P<0.05），12 h降至最低（均n P<0.05）。MCAO术后12 h起可见RGMa和突触素阳性表达并随时间延长持续增加，48 h表达达高峰，而MCAO术后各组轴突表达逐渐减少，24 h组破坏最为明显，以上各指标表达变化梗死对侧（右侧）小脑均较患侧（左侧）小脑明显（均n P<0.05）。RGMa蛋白表达与磁共振参数及轴突生长情况呈显著负相关（n r=-0.312，n P=0.004）。n 结论:RGMa蛋白可能参与缺血性脑梗死后轴突和突触的再生与重塑，磁共振检查可作为无创性监测脑梗死及神经功能的评估手段。“,”Objective:By using magnetic resonance diffusion tensor imaging (DTI) as an approach of dynamic continuous monitoring in vivo, we aimed to investigate how the repulsive guidance molecule A (RGMa) expression in the primary lesion and remote regions after ischemic cerebral infarction in rat brain tissues relates to axonal regeneration, synaptic remodeling and magnetic resonance imaging (MRI) parameters, as well as its role in neural rehabilitation and regulation, and to propose an effective, non-invasive option for imaging studies.Methods:Seventy-two SD rats were randomly divided into the control group and postoperative 12 h, 24 h, 48 h, 7 d, 10 d groups with middle cerebral artery embolization (MCAO) (n n=12 each) . At each corresponding time points, the rats underwent head MRI scan for measurement of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the primary lesion and bilateral cerebella. After scanning, the study parts of rat brain tissues were harvested and subjected to RT-PCR and immunohistochemical study for RGMa expression. In each group of rats, immunohistochemistry was used to examine the axon regeneration and synaptic remodeling; transmission electron microscopy was used to observe the cell ultrastructural changes in the rats. Spearman correlation analysis was used to analyze the correlations among RGMa protein and neurofilament protein (NFP-200) , ADC and FA values in the primary lesion and bilateral cerebella of rats with cerebral infarction.n Results:The ADC and FA values of the primary lesions and bilateral cerebella of rats at any given time point after ischemic cerebral infarction were lower than those in the control group (all n P<0.05) , with the lowest values noted at 12 h (alln P<0.05) . Positive expression of RGMa and synaptophysin was detectable at 12 h after MCAO, continued to increase with time, and peaked at 48 h. The expression of axons in each group after MCAO decreased gradually, and the damage was the most prominent in the 24 h group. These expression profiles were more remarkable in the contralateral (right) than in the affected (left) cerebellum (alln P<0.05) . The expression of RGMa protein was in significant negative correlation with MRI parameters and axonal growth (n r=-0.312, n P=0.004) .n Conclusion:RGMa protein may be involved in the regeneration and remodeling of axons and synapses after ischemic cerebral infarction. MRI can be used as a tool for noninvasive monitoring of cerebral infarction and evaluation of neurological functions.