MR弥散成像在脑梗死诊断中的应用

目的:探讨弥散加权成像(DWI)、表观扩散系数(ADC)图在诊断超急性、急性脑梗死、脑干梗死及皮层下脑梗死中的应用价值.方法:应用单次激发平面回波DWI和常规MRI对100例脑梗死患者进行检查.其中超急性期10例,急性期18例,亚急性期50例,稳定期12例,慢性期10例.19例脑梗死患者进行了常规CT检查.观察各期脑梗死、多发脑梗死、脑干梗死及皮层下脑梗死在CT、常规MRI及弥散图像上的表现,测定梗死灶ADC值,同时测定对侧相应部位正常脑组织ADC值.结果:超急性、急性期脑梗死在DWI上表现为高信号,在T2WI上为等信号或表现为部分稍高信号,在ADC图上表现为低信号,病灶ADC值较对侧相应区域明显下降,梗死灶ADC值与对侧相应部位正常脑组织ADC值差异有显著意义(P＜0.01).结论:脑梗死灶在DWI及ADC图上具有特征性演变规律,结合T2WI可以对脑梗死进行分期诊断.DWI有助于超早期脑梗死的诊断、多发脑梗死中新旧病灶的区分、脑干梗死及皮层下脑梗死的检出,对临床个体化治疗方案的制定有极大帮助.DWI较CT敏感,亦较常规MRI敏感,对疑有急性期尤其是超急性期脑梗死者,应加作DWI检查.

Application of MR diffusion weighted imaging in cerebral infarction

Objective:To study the roles of diffusion weighted imaging(DWI)and apparent diffusion coefficients(ADC) mapping in diagnosing superacute cerebral infarction,brainstem infarction and subcortical cerebral infarction.Methods:One hundred patients with cerebral infarction(10 superacute,18 acute,50 subacute,12 steady,and 10 chronic)were imaged with both conventional MRI and single-shot echo-planar diffusion weighted imaging.Ninteen patiens with cerebral infarction were imaged with CT.The appearance of infarct including each stages,multi-infarct,brainstem infarction and subcortical cerebral infarction in DWI,T2WI and CT was analyzed.The ADC of each stage lesion and corresponding contralateral brain tissue were calculated.Results:Hyperacute and acute infarcts appeared as areas of hyperintensity on DWI,nomal or slightly hyperintensity on T2WI,hypointensity on ADC.The ADC of lesion was significantly depressed compared with that of contralateral tissue.There was positive correlation between infarct lesion and corresponding contralateral normal brain tissue(P<0.01).Conclusion:The appearance of cerebral infarction in DWI and ADC mapping has characteristic developing regularity.Combined with T2WI can differentiate different stages of infarction.DWI and ADC mapping assist to diagnose hyperacute and acute cerebal infarction,to distinguish new or old lesion in polyinfarction,to detect brainstem infarction and subcortical cerebral infarction,to formulate individualized treatment plan.DWI is more sensitive than CT and conventional MRI.If someone was suspect hyperacute and acute cerebral infarcion,one should have DWI examination.