病毒性脑炎的核磁共振成像、扩散加权成像和质子MR波谱表现

MRI, DWI and ^1H-MRS features of viral encephalitis： report of 36 cases

目的探讨病毒性脑炎的核磁共振成像(magnetic resonance imaging,MRI)、扩散加权成像(diffusion weighted imaging,DWI)和质子MR波谱(1Hmagnetic resonance spectroscopy,1H-MRS)表现。方法36例病毒性脑炎在急性或亚急性阶段接受了常规MRI、DWI及2D1H-MRS检查。总结病毒性脑炎常规MRI、DWI及1H-MRS表现特点,比较病毒性脑炎和对侧正常脑组织的表观弥散系数值(ADC)、胆碱(Cho)、N-乙酰天门冬氨酸(NAA)、肌酸(Cr)差异有无统计学意义。结果病灶表现多发22例,单发14例,可累及皮层、皮层下、侧脑室周围白质以及基底节-丘脑区。T1WI呈稍低信号,T2WI呈高信号,可有轻度斑片状强化。DWI上呈等或稍高信号11例,均匀高信号4例,不均匀高信号21例。ADC伪彩图上26例扩散加快,另外10例扩散加快与受限同时存在。病毒性脑炎ADC值[(0.93±0.29)×10-3mm2/s]较对侧脑白质[(0.76±0.32)×10-3mm2/s]升高,差异有统计学意义(P=0.007)。病毒性脑炎的Cho、Cr和NAA分别为(364.3±56.3)、(178.4±28.2)、(203.7±33.8),较对侧[分别为(440.2±52.8)、(269.3±37.5)、(386.5±68.5)]相应波峰降低,差异有统计学意义(P<0.01,P<0.05),有3例见Lac峰。结论DWI、1H-MRS反映了病毒性脑炎的组织及代谢特点,是常规MRI有益的补充。

Objective To explore the radiological manifestations of viral encephalitides by magnetic resonance imaging （MRI）, diffusion weighted imaging （DWI） and ^1H magnetic resonance spectroscopy （ ^1H-MRS）. Methods The conventional MR imaging, DWI and muhivoxel 2D ^1H-MRS were performed in 36 cases with acute or subacute viral encephalitis. The data by DWI and ^1H-MRS were calculated and analyzed, and statistical analyses were performed by using the software of SAS 8.2. Results Viral encephalitis presented as single （14 cases） or multiple lesions （22 cases）, located mainly in cortices, subcortical and periventricular white matter, basal ganglia and thalami. The lesions carried slightly long T1 and long T2 intensity with faint patch shape enhancement on contrast-enhanced image. Abnormalities were found on DWI, including isointensity or slightly hyperintensity in 11 cases, homogeneous hyperintensity in 4 cases, and inhomogeneous hyperintensity in 21 cases. On apparent diffuse coefficient （ADC） map, increased diffusivity of the lesion were demonstrated in 26 cases, and increased and restricted diffusivity were seen in the other 10 cases. The mean ADC value of viral encephalitis was significantly higher than that of normal control tissues [ （0.93 ± 0.29 ）×10^-3 and （0.76 ±0.32）×10^-3 mm^2/s, P = 0. 007 ]. On ^1H-MRS, choline （ Cho）, creatin （Cr） and n-acetyl aspartate （NAA） of viral encephalitis were significantly lower than those of normal control tissues [ Cho （364.3 ± 56.3 ） vs （440.2±52.8）, P〈0.01; Cr （178.4±28.2） vs （269.3±37.5）, P〈0.05; NAA （203.7±33.8） vs （386.5±68.5）, P 〈 0.01 ]. Lactate peak was found in 3 cases. Conclusion DWI and ^1H-MRS present the information for the histological and metabolism feature of viral encephalitis, and should be applied as an important supplemental examination besides conventional MRI.