小脑区病变MRI诊断分析

目的 对后颅凹小脑区病变的MRI诊断和鉴别诊断进行分析，并讨论部分影像诊断进展。材料和方法 收集我院近2年手术病例43例，复习MRI平扫和增强扫描影像资料。结果 本组43例中，非占位性病变：小脑半球梗塞2例，MRI呈长T1长T2脑回状异常信号，如伴出血则形成短T1长T2信号，增强扫描可有脑回状强化。动静脉畸形（A－VM）3例，长T1长T2异常信号中可见蔓状“血管流空”征象（T2WI）引流静脉T2WI可见高信号，钙化和含铁血黄素沉着，CT检查有助诊断。小脑区占位性病变38例，其中星形细胞瘤5例，血管母细胞瘤7例，桥小脑角区听神经瘤13例，髓母细胞瘤4例，桥小脑角区脑膜瘤2例，室管膜瘤2例，小脑转移瘤5例，肿瘤占位效应明显，边缘多较清楚，T1WI呈等低信号，T2WI多呈等高异常信号，增强后明显强化，但小脑区肿瘤发生和年龄、发生部位、形态和周围组织有密切关系，如星形细胞瘤年龄较低，转移瘤年龄较高，髓母细胞瘤多居小脑蚓部正中线，室管膜瘤多于四脑室内，四脑室受压常可引起幕上脑室扩大（积水）。血管母细胞瘤多见囊变、坏死、脑膜瘤强化后可见脑膜尾征。MRI对小脑区病变的检出率、定位率可达100％。结论 MRI对后颅凹检查无骨质伪影干扰，对小脑区病变的诊断和鉴别诊断有重要价值，并对脑膜转移瘤的诊断有独特作用。

MRI Diagnosis of Cerebelum Lesions

Objective: To study MRI diagnosis and the differential diagnosis of cerebellum Lesions as well as to investigatethe progress in partial radiologic diagnosis.Materials and Methods: Wecollected 45 cases of cerebellum lesions which were verified by operation in our hospital,and reviewed the radiolosic data of scan and enhanced scan. Results: Among 43 cases,5 cases were not occupying lesions,2 of cerebellum hemisphere infarction,3 of A VM.38 cases were.Cerebellum occupying lesions,5 of astrocytomas,7 of hemangioblastoms,13 of pontocerebellor acoustic tumors,2 of epenaymoma,4 of medulloblastomas,2 of pontocerebellar meningioms,2 of ependymoma,and 5 of metastasis,The tumours were clear outline and evident mass effect.Most of them were low or equal signal on T 1WI,high signal on T 2WI.They could be enhanced conspicuously after contrast.The incidence of cerebellum tumours were strongly correlated with age,location,mophology and surrounding tissue.The accuracy rates of detection and localization of the cerebellum lesion were 100% by MRI technique. Conclusion: There is no bone matrix artifact disturbing in detect cerebelhm lesions by MRI.It is important to use MRI techniqne in diagnosis and differential diagnosis of the cerebellum lesions,particularly in diagnosis meninges metastatic tumours.