后颅凹非典型室管膜瘤的CT和MR诊断

CT and MRI diagnosis of posterior fossa atypical ependymoma

目的 分析后颅凹非典型性室管膜瘤的CT和MR影像学特点。方法 16例经手术病理证实的后颅凹非典型性室管膜瘤,行CT和(或)MR检查。男11例,女5例。年龄17～46岁,平均312岁,其中20～40岁者12例。临床主要表现眩晕、走路不稳和呕吐。结果 病灶12例位于小脑半球,3例位于小脑蚓部,1例位于桥小脑角。15例肿瘤为实质性,实质内有多灶性坏死囊变,1例呈囊性,位于桥小脑角。肿瘤多靠近小脑表面,与硬脑膜或小脑幕有较长的连接面。3例肿瘤内有钙化。CT扫描呈不均质混杂密度,MR扫描呈不均质混杂信号。增强扫描多呈轻度斑片状不均质强化,少数呈显著多环样不规则强化。结论 后颅凹非典型性室管膜瘤的特点是肿瘤位于小脑实质,多数肿瘤呈实质性,内有多发小灶性坏死囊变,CT和MR表现为混杂密度和混杂信号。鉴别诊断应考虑脑膜瘤、转移瘤和听神经瘤。

Objective ToanalysetheCTandMRIfeaturesofposteriorfossaatypicalependymoma Methods SixteencasesofposteriorfossaatypicalependymomaprovedbysurgeryandpathologyhadCTand(or) MRIscanning Therewere 11malesand 5females Theagerangedfrom 17to 4 6(mean ,3 1 2 ) Twelvecases rangedfrom 2 0to 4 0yearsold Themainsymptomsofallcasesweredizziness ,unsteadywalkingandvomiting Results Thelocationsofallcaseswerecerebellum ( 12cases) ,vermis ( 3cases)andcerebellopontileangle ( 1case) Fifteencasesweresolidwithmultiplecysticchangesand 1caseinthecerebellopontileanglewascystic Thetumorwasusuallyclosetothesurfaceofcerebellumwithratherextensiveconnectionwithduramateror tentorium Calcificationswereshownin 3cases ThetumorsrevealedinhomogeneousdensityonCTscanand inhomogeneousintensityonMRI Mildinhomogeneousenhancementwasshowninmostcases,whileintense irregularenhancementintheothers Conclusions Thecharacteristicfindingsoftheposteriorfossaatypical ependymomaependymomawerecerebellarintraparenchymalmultiplesmallcysticchangeswithinsolidtumorin mostcasesandinhomogeneousdensityandintensityonCTandMRI Thedifferentialdiagnosisismeningioma , metastasisandacousticschwannoma