弥散加权成像在儿童病毒性脑炎中的诊断价值

Diagnostic value of diffusion-weighted imaging in children with viral encephalitis

目的:探讨弥散加权成像在儿童病毒性脑炎诊断中的价值。方法:对临床确诊的34例儿童病毒性脑炎行常规T1WI、T2WI、液体反转恢复序列(FLAIR)和弥散加权成像(DWI)横断面扫描。根据常规MRI与DWI显示病变数目、范围、信号强度的对照分三组,与发病时间相结合计算并比较每组病灶各种检查序列的对比噪声比(CNR)。结果:依据显示脑炎效果分:Ⅰ组(n=10)DWI优于常规MRI,发病时间平均(3.1±1.4)天;Ⅱ组(n=9)DWI与常规MRI基本一致,发病时间平均(5.6±1.9)天;Ⅲ组(n=15)常规MRI优于DWI,发病时间平均(15.3±7.7)天。Ⅰ组中DWI的CNR均明显高于T1WI、T2WI、FLAIR(P<0.01);Ⅱ组DWI的CNR与其它三个序列均无明显差异(P>0.05);Ⅲ组DWI的CNR明显低于T2WI(P=0.022<0.05),与T1WI、FLAIR的CNR均无明显差异(P>0.05)。结论:在儿童病毒性脑炎早期,DWI的CNR高于T1WI、T2WI、FLAIR;随发病时间延长,DWI的CNR低于T2WI。弥散加权成像在儿童病毒性脑炎早期诊断中具有重要作用。

Objective：The objective of the study was to evaluate the diagnostic value of diffusion-weighted imaging in children with viral encephalitis. Methods：We performed conventional magnetic resonance imaging （MRI） including T1WI, T2WI and fluid attenuated inversion recovery （FLAIR） sequences and DWI in 34 children with viral eneephalitis diagnosed on the basis of clinic. Based on the qualitative and quantitative comparison of the conventional MRI and DWI, the patients were divided into three groups. The absolute values of CNRs of lesions on T1WWI, T2WI, FLAIR and DWI were computed and compared for eaeh group,eombing with the time from tile onset of neurologie symptoms to the MR examination.Results：In group Ⅰ （n = 10） DWI was superior to conventional MRI in showing the eneephalitie involved sites. The interval time of the illness was （3.1 ±1.4） days; In group Ⅱ （n= 9） DWI was similar to eonventional MRI,time was（5.6±1.9） days. In group Ⅲ （n= 15） conventional MRI was superior to DWI, time was（15.3 ±7.7）days. In group Ⅰ, The absolue CNRs on DW images were signifieandy higher than those on T1W, T2W and FLAIR images （ P 〈 0.01 ） ; In group Ⅱ, absolute CNRs on DW images have no signifieantly different from those on other imges（ P 〉 0.05） ; however, lesions on DW images in group Ⅲ have signifieantly lower CNRs than on T2W （ P = 0.022〈 0.05）,but have no signifieantly different from those on TIW and FLAIR images（ P 〉 0.05）. Conclusion：The absolue CNRs on DW images were significantly higher than those on T1W, T2W and FLAIR images in the early stage of viral encephalitis in ehildren and lower than T2WI with the duration of the disease. Diffnsion-weighted images have an important role in the early diagnosis of viral eneephalitis in ehildren.