肿瘤软脑膜-蛛网膜转移的CT、MRI诊断

目的研究肿瘤软脑膜蛛网膜转移的ＣＴ、ＭＲＩ表现，并探讨两种检查方法对该病的诊断价值。方法回顾分析２１例肿瘤软脑膜蛛网膜转移的临床及影像学资料。病变经ＣＴ检查１６例，ＭＲＩ检查７例，其中经两种方法检查者２例。结果全部病例软脑膜蛛网膜下腔均出现病理性强化，其中１０例呈弥漫性，８例呈结节性，３例呈弥漫与结节混合性。弥漫性强化沿脑和脑干表面分布，并延伸入脑沟、脑池；结节性强化病灶数目１个或多个不等，直径０．２～３．０ｃｍ。病变见于基底脑池及相邻蛛网膜下腔者共１８例。伴室管膜结节性强化４例，天幕增厚强化１０例，脑积水１３例，合并脑内转移９例。结论增强ＣＴ和ＭＲＩ对病变的诊断具有重要临床意义，且ＭＲＩ优于ＣＴ。但两者在定性诊断上均有局限性。正确诊断有赖于结合临床资料和影像征象的综合分析

CT and MR imaging in the evaluation of leptomeningeal metastases

Objective To study the manifestations of leptomeningeal metastases on CT and MR imaging, and evaluate the diagnostic significance of both modalities for this disease. Methods Clinical and neuroradiological data of 21 cases with leptomeningeal metastases were retrospectively reviewed. In this series, 16 patients were studied by CT and 7 patients by MRI, 2 patients by both CT and MRI. Results Abnormal enhancement of pia and subarachnoid space, appearing as diffuse pattern in 10 cases, nodular pattern in 8 cases and mixed pattern with diffuse plus nodules in 3 cases, were visualized by CE CT and Gd MRI. Diffuse enhancement followed the convolutions of gyri and surface of brainstem, and extended into cerebral cisterns and sulci. The foci appeared as enhanced nodules 0.2-3.0 cm in diameter and 1 or more in number. Nodules with infiltration of cerebral parenchymal were found in 4 patients. In 86% of all cases, diffuse or nodular foci occurred in basilar cysterns and adjacent cerebellar and cerebral sulci. There were 4 cases associated with ependymal nodular enhancement and 10 cases with widened irregular tentorial enhancement. Intracerebral metastases in 9 cases and hydrocephalus in 13 cases were found in this series. Conclusions CE CT and Gd MRI are had significant clinical dignostic value for leptomeningeal metastases, Gd MRI is superior to CE CT. Because of the limitation in the evaluation of leptomeningeal invasion by neoplasms on CT and MRI, definitive diagnosis of leptomeningeal metastases depends on combination of clinical and imaging data.