磁共振扩散加权成像在小儿病毒性脑炎中的诊断价值

目的:评价磁共振扩散加权成像(DWI)对小儿病毒性脑炎的诊断价值,并观察表观扩散系数(ADC)的变化规律。方法:对38例临床明确诊断的小儿急性期病毒性脑炎,分别作轴位DWI和常规T1WI、T2WI成像。观察病毒性脑炎在DWI与常规T2WI的表现,同时测量感兴趣区域和正常同龄段儿童脑白质和脑灰质的ADC值。结果:MRI诊断20例阳性,共发现76个病灶。3个病灶在DWI出现异常高信号而T1WI、T2WI均未见明显异常信号,52个病灶在DWI与T2WI均表现为高信号,其中25个病灶DWI显示范围较T2WI更清楚、更广泛,13个病灶在DWI表现为等信号,在T2WI为高信号,8个病灶在DWI表现为低或稍低信号,在T2WI为高信号。复查11例其中7例痊愈,其余4例出现11个软化灶,在T2WI表现为异常高信号,在DWI表现为低信号,T1WI表现为低信号。结论:DWI能在早期发现病毒性脑炎异常信号,也能够反应病毒性脑炎不同时期的病理变化,与常规T2WI相比可提供定量的诊断信息,对疾病的诊断及预后疗效评估也有一定价值。

Diagnostic value of diffusion-weighted MR imaging in children with virus encephalitis

Objective: To evaluate the diagnostic value of DWI in children with virus encephalitis and to observe the ADC values. Methods: Thirty-eight cases with acute viral encephalitis were included. DWI and conventional T1WI, T2WI sequences were performed in all cases. The appearances on DWI, T1WI and T2WI were recorded. The ADC values of lesions were calculated, which were compared with normal ADC values of gray matter and white matter of healthy children. Results: Twenty cases had positive findings on MRI with 76 lesions detected. Three lesions showed high signal intensity on DWI but were normal on T1WI and T2WI. Fifty-two lesions showed high signal intensity on both DWI and T2WI, but 25 showed clearer and more distinct on DWI than on T2WI. Thirteen lesions showed isointense on DWI, with high signal intensity on T2WI. Eight lesions showed hypointense on DWI with high signal intensity on T2WI. Of the 11 follow-up cases, 11 encephalomalacia lesions were detected in 4 cases, which showed long T1 and long T2 signal intensity with low signal intensity on DWI. Conclusion: DWI can serve as a method of detecting early viral encephalitis, in which DWI could give quantitative information for different pathological changes in different clinical stage. DWI has great potential value in the diagnosis, differential diagnosis and the prediction of prognosis in viral encephalitis.