弥散加权成像在超急性期脑梗死诊断中的应用

目的 将磁共振弥散加权成像（DWI）与常规MR技术作对比。评价DWI对超急性期脑梗死诊断的准确性和敏感性。方法 对52例超急性期，急性期，亚急性期，慢性期的患者行DWI，快速自旋回波T2WI，FLAIR及3DTOF法磁共振血管成像检查。对所有病例的病变部位均按神经解剖进行准确定位并与患者的症状，体征相联系。结果 超急性期和急性期脑梗死在DWI图像上表现为高信号，在表观弥散系数（ADC）图上表现为低信号，ADC值低于对侧相应的区域。在超急性期和急性期，病灶的ADC值显著下降,rADC值也明显下降。平均下降约59.12%。而在慢性期ADC值明显升高，甚至较正常组织还高，平均升高达20.3%。结论 DWI对6h症状起病的急性卒中的诊断明显高于传统MRI，DWI可以在超急期发现缺血病灶，早于常规T2WI及FLAR序列图像。DWI对脑梗死的早期诊断及评价起重要的作用。

Study on diffusion-weighted imaging in the diagnosis of hyperacute cerebral infarction

Objective In this study we compared the sensitivity of DWI with that of conventional MRI techniques,so as to evaluate the diagnostic accuracy of diffusion weighted magnetic resonance(MR) imaging performed within 6 hours of the onset of stroke symptoms. Methods We performed DWI,fluid attenuated inversion recovery,fast spin echo T 2 weighted MRI,3D TOF MRA in 52 patients with hyperacute,acute,subacute,chronic stroke. In all cases,the neuroanatomic locations of the lesions were precisely determined,and an experienced neurologist judged if the location of the lesion seen on MRI was in agreement with the patient's symptoms and signs. Results Hyperacute and acute infarcts appeared as areas of hyperintensity on DW images and hypointensity on ADC map,the ADC value was less than that of contralateral corresponding region. In hyperacute and acute stage,ADC decreased and rADC decreased by 59.12%;in contrast,it increased by 20.3% in chronic stage. Conclusion Diffusion weighted MR imaging is highly accurate for diagnosing stroke within 6 hours of symptom onset and is superior to conventional MR imaging. DWI could demonstrate ischemic area at early stage,much earlier than T 2WI and FLAIR. DWI plays an important role in making early diagnosis and evaluation of cerebral infarction.