病毒性脑炎的MRI表现及临床价值

MRI findings and clinical study of virus encephalitis cases

ZHOU Wen-hui,LIU Si-bin, CHEN Hua-bin

Department of Radiology,Jingzhou Hospital,Tongji Medical College,Huazhong University of Science and Technology,Jingzhou 434020， China

[Abstract] Objective To study MRI features of virus encephalitis, and assess the diagnosis value of MRI in virus encephalitis.  Methods MRI and clinical manifestations of 25 patients with virus encephalitis confirmed clinically were analyzed.All patients were imaged by MR scanner with SE T1WI、FSE T2WI、FLAIR、Gd-DTPA enhanced T1WI. Results 22 of 25 cases were diagnosed as virus encephalitis by MRI.Their MR features included;slightly low or moderate signal intensity on T1WI ,slightly high signal on T2WI and significantly high intensity on FLAIR.10 of 25 cases were confirmed as herpes simplex encephalitis.These lesions were distributed mainly over both frontal and temporal lobes and had a clear boundary with lenticula.Misdiagnosis cases included:cerebral infarction(1 cases),cerebral schistosomiasis (1 cases)and demyelinating lesions(2 cases). Conclusion MRI can evaluate virus encephalitis and show the extent of lesion clearly.MRI scanning is the first way to diagnose in all of imaging.Some virus encephailitis cases with complicated MR features should be differentiated with other diseases.Analyzing comprehensively the MRIfindings in virus encephailitis may provide to a certain extene,evidences for clinical diagnosis,evaluation of clinical grading and prognosis.

[Key words]:virus encephalitis;magnetic resonance imaging

病毒性脑炎是一种较常见的中枢神经系统感染性病变，其临床表现往往不具有特征性，需结合临床症状、脑脊液检查及影像学检查作出诊断。MRI对病毒性脑炎的显示较CT更具有优势，在病变部位、范围、程度等方面为临床提供了极有价值的诊断信息[1]。本文回顾性分析了25例经临床证实的病毒性脑炎的MRI表现，并对病毒性脑炎的MRI诊断价值和鉴别诊断进行讨论。

材料与方法

1 一般资料

搜集本院1998年3月-2005年6月经临床证实且影像学资料完整的病毒性脑炎患者25例，其中男11例，女14例，年龄7-67岁。临床表现：发热13例，头痛19例，意识障碍3例，癫痫9例，肢体运动障碍12例，视力障碍4例。脑膜刺激征2例。实验室脑脊液检查：颅内压增高15例，红细胞增多11例，白细胞增多12例，蛋白增高19例。病毒免疫学检查确诊为单纯疱疹病毒性脑炎10例。所有病例经过临床抗病毒治疗症状好转或完全治愈。其中有15例治疗后1-2月复查MRI。

2 扫描方法

使用GE Signa 0.5T超导磁共振仪，25例均行常规MRI平扫与增强扫描。平扫包括矢状位SE序列T1WI:TR500ms、TE20ms，轴位SE序列T1WI:TR500ms、TE15ms,FSE序列T2WI:TR2940ms、TE88ms,FLAIR:TR6800ms、TE105ms。增强扫描为轴位、冠状位、矢状位SE序列T1WI:TR500ms、TE15ms。层厚8mm，层间1mm，激励2次。增强Gd-DTPA的用量为0.1mmol/kg。

结果

25例中22例MRI诊断和临床相符。MRI表现(图1-3)：①病灶部位：颞叶18例，额叶12例，顶叶13例，枕叶7例，脑干2例，小脑3例。位置表浅，皮层和皮层下区以及白质区均可累及。②病灶形态：多数无具体形状，为点状、斑片状，少数为结节状。③病灶数目、大小：病灶多发，散在，大小不一。④病灶信号：T₁WI呈等或稍低信号，T₂WI呈稍高或高信号，FLAIR序列呈明显高信号，同时比T2WI序列病灶范围和数目增大增多者3例。⑤增强效应：无明显强化7例，斑点状强化9例，斑片状或结节状强化6例，脑回状强化3例，伴脑膜强化3例。⑥占位效应：17例有明显占位，8例占位不明显。⑦MRI复查：11例病灶缩小，数目减少，3例病灶消失，1例病灶范围扩大，1例病灶位置改变。⑧2例病灶广泛，幕上幕下多叶受累，一月后出现病情反复，伴轻度脑萎缩，病程超过90天。

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