中颅窝区脑外肿瘤的MRI表现  

Magnetic resonance imaging-based diagnosis of middle cranial fossa tumors

作　　者：段刚[1] 彭旭红[1] 

机构地区：[1]南方医科大学南方医院影像中心,广州510515

出　　处：《中华神经医学杂志》2009年第7期708-711,共4页Chinese Journal of Neuromedicine

摘　　要：目的探讨中颅窝区脑外肿瘤的MRI特点，提高其诊断准确率。方法经手术病理证实的31例中颅窝区脑外肿瘤（包括三叉神经鞘瘤13例，脑膜瘤6例，蛛网膜囊肿3例，皮样囊肿3例，骨母细胞瘤2例，脊索瘤2例，表皮样囊肿2例1均行MR平扫及增强扫描检查，并对其影像资料进行回顾性分析。结果不同的中颅窝区脑外肿瘤各具不同MR特征：（1）三叉神经鞘瘤MRI T1WI像多呈等或低混杂信号，T2WI像呈高或低混杂信号，本组13例三叉神经鞘瘤增强后有9例可见“包壳征”；（2）脑膜瘤多表现为等或稍低T1、等或低或高T2信号，增强后呈中度较均匀强化；（3）骨母细胞瘤可见“骨包壳”，脊索瘤骑跨中、后颅窝生长，其一侧与斜坡紧密相连；（4）蛛网膜囊肿与表皮样囊肿均呈长T1、长T2囊状信号，增强后无强化或囊壁轻微强化；蛛网膜囊肿多呈膨胀生长，而表皮样囊肿多有“见缝就钻”的特点；（5）皮样囊肿均呈短T1、长T2囊状信号，脂肪抑制序列扫描呈低信号，可出现“爆米花”样改变。结论中颅窝区脑外肿瘤均有比较特征性的MRI表现，密切结合临床可进一步提高其术前诊断的正确率。Objective To analyze the magnetic resonance imaging （MRI） features of middle cranial fossa tumors. Methods Thirty-one patients with surgically and pathologically confirmed middle cranial fossa tumors were enrolled in this study, including 13 with trigeminal neurinomas, 6 with meningiomas, 3 with arachnoid cysts, 3 with dermoid cysts, 2 with osteoblastomas, 2 with chordomas, and 2 with epidcrmoid cysts. All the patients underwent plain and enhanced MR scanning and the imaging data were retrospectively analyzed. Results Different types of middle cranial fossa tumors had distinctly different MR/appearances. Trigeminal neuromas displayed hypo- and iso-intense signals on T 1-weighted images （T 1WI） and hyperintense signals on T2-weighted images （T2WI）, and 9 of the 13 patients presented with shell-shaped enhancement after Gd-DTPA injection. Meningioma showed hypo-and iso-intense signals on T1WI and hypo-, iso- and hyper-intense signals on T2WI, with relatively homogeneous enhancement after Gd-DTPA injection. Osteoblastoma exhibited shell-shaped bony encapsulation of the tumor, and chordomas grew along the middle and posterior cranial fossae with close lateral association with the clivus. Arachnoid cysts and epidermoid cysts showed hypointense signals on T1WI and hyperintense signals on T2WI with slight enhancement of the cyst wall after Gd-DTPA injection. The arachnoid cysts grew expansively, and epidermoid cysts were characterized by high invasiveness in any possible directions. Dermoid cysts presented with hyperintense signals on T1WI and T2WI with popcorn-like appearance in some cases. Conclusion The middle fossa tumors present characteristic MRI features, which, in combination with clinical examinations, help derive an accurate diagnosis.

关 键 词：中颅窝 三叉神经鞘瘤 脑膜瘤 骨母细胞瘤 蛛网膜囊肿 表皮样囊肿 皮样囊肿 磁共振成像 

分 类 号：R686[医药卫生—骨科学]