脑膜瘤的MRI诊断价值(附60例分析)

目的：研究脑膜瘤的MRI影像特征，提高脑膜瘤的正确诊断率。方法：回顾分析2006．7—2007．6经病理确诊的脑膜瘤患者60例，男22例，女38例，最小年龄6岁，最大81岁，平均年龄34岁。全部病例均行MRIT1、T2加权及增强扫描。分别就脑膜瘤发生部位、病变大小、病变形态、信号特点、肿瘤常见征象、增强特点、脑外定位判断等方面进行总结结果：以大脑凸面最多，27例，约占45％；其次为鞍区11例（18．3％），桥小脑角区8例（13．3％），小脑幕6例（10％），蝶骨嵴5例（8．3％），其余4例（6．7％）。病变直径：在（0．8—8．6）cm之间，平均3．8cm。病变形态：圆形和类圆形占82％，分叶及不规则占18％。信号特点：T1加权信号以等和略低信号为主，占66．7％，低信号26．7％，略高和高信号6．7％。T2加权信号以等信号和略高信号最多，约占70％，高信号26％，混杂信号4％。肿瘤征象：脑膜尾征出现率为51．7％，假包膜出现率为48．3％，脑实质挤压征出现率达38．3％。瘤周水肿出现率达43．3％。其它少见的征象包括囊变、出血、钙化和瘤内血管征等。增强特点：明显均匀性增强占86．7％，明显不均匀性增强占13．3％。脑外定位判定：本组35％的脑膜瘤脑脊液一血管周围间隙明显较对侧增大。50％的脑膜瘤以广基与硬脑膜相连，肿瘤与硬脑膜相连处常为钝角。1／3多的肿瘤表现为脑实质挤压征。少数肿瘤可以出现静脉窦阻塞和脑外动脉包绕。这些征象可以作为脑外肿瘤的定位判断。结论：全面分析肿瘤发生部位、病变形态、信号特点、肿瘤常见征象、增强特点、脑外定位判断，可以提高脑膜瘤的正确诊断率，尤其是脑实质外肿瘤的判定、T1WI及T2WI的典型信号、脑膜尾征、假包膜和明显均匀强化是诊断脑膜瘤的关键。

The diagnosis of magnetic resonance imaging of meningoma(A report of 60 cases)

Objective:To study the character of magnetic resonance imaging(MRI)of meningoma,in order to improve the correct rate.Methods:Retrospective analysis of 60 patients who confirmed by pathology in our hospital from June 2006 to July 2007.Male 22,female 38,age from 6 to 81years old,average was 34.All the cases were scanned with T1,T2 weight imaging(T1WI,T2WI) and contrast-enhancementT1WI.To summarize the character of MRI including location,size,character of signal,signs of tumor,information of contrast-enhancement and how to discriminate the tumor was an extra-brain tumor.Results:Location:among the 60 cases,45% tumors located in convexity of brain,and following were in saddle area,cerebellopontine angle,tentorium of cerebellum and crista sphenoidalis,the rate of them were 18.3%,13.3%,10%,8.3%,respectively.The others were 6.7%.Size:from 0.8cm to 8.6cm,average was 3.8cm.Figure of tumor:round and similar round were 82%,sublobe and irregular were 18%.Character of signal:equation and slight low signal were dominate,about 66.7%,low signal was 26.7%,slight high and high signal were 6.7% on T1WI.Equation and slight high signal were 70%,high signal was 25%,and mix signal was 5% on T2WI.Signs of tumor:the rate of tail sign was 51.7%,pseudo-capsule was 48.3%,edema of tumor occurred in 43.3% cases.Other rare signs included cystic,bleeding,calcification,and vessel symptom of tumor.Information of contrast-enhancement:obvious and even enhancement was 86.7%,obvious but uneven was 13.3%.Evidence of extra-brain tumor:among the 60 cases,cerebrospinal fluid and perivascular space was wider than opposite side in 35% tumors.Tumors that connected to cerebral dura mater with a wide fundament were in 50% cases.Extruding sign brain parenchyma was found in more than 38% cases.Blockage of sinus venous and circumvolution of out- brain artery were found in some tumors.All of the signs can be used to judge the tumor was an extra-brain tumor.Conclusion:To analyze the character of MRI including location,figure,character of signal,signs of tumor,information of contrast-enhancement and how to discriminate the tumor is an extra-brain tumor can help to improve the correct diagnostic rate of meningoma,especially judgment of extra-brain tumor,typical signal on T1WI and T2WI,tail sign,significantly and even enhanced sign are the key factors for diagnosis of meningoma.