桥小脑角区肿瘤的MRI诊断和鉴别诊断

目的 探讨桥小脑角区肿瘤MRI的特征、诊断和鉴别诊断。方法 回顾性分析34例经手术和病理证实的桥小脑角区肿瘤的MRI资料，采用T1-SE序列，T2-FSE序列，所有患者均常规行横断面T1WI、T2WI及冠状面T1WI，必要时矢状面T2WI，其中28例加做Gd-DTPA增强扫描。结果 23例听神经瘤中16例听神经增粗并向内耳道延伸，为听神经瘤的典型征象：4例三叉神经瘤均跨中、后颅窝生长呈哑铃状：3例脑膜瘤中1例增强后出现“脑膜尾征”；1例室管膜瘤呈类圆形，与第四脑室出口关系密切；1例蛛网膜囊肿边缘光滑，信号类似脑脊液；1例胆脂瘤边缘光滑，信号均匀，沿桥脑池生长；1例海绵状血管瘤无典型征象。34例桥小脑角区肿瘤术前定位、定性诊断准确率分别为100％、91．2％。结论 MRI是桥小角区肿瘤检查的首选方法，对桥小脑角区肿瘤的诊断和鉴别诊断有重要价值。

Diagnosis and differential diagnosis of tumors in cerebellopontine angle using MRI

Objective To probe characteristics, diagnosis and differential diagnosis of tumors in cerebellopontine angle on MRI. Methods Clinical data and MRI results of 34 cases with pontocerebellar tumors proved by operational or pathological examination were retrospectively analyzed. 1.5 T MRI scanner, conventional T1 spin echo sequence and T2 fast spin echo sequence were used. Axial T1-weighted images, axial T2-weighted images, coronal T1-weighted images and sagittal T1-weighted images of all patients were obtained. 28 patients underwent Gd-DTPA enhancement. Results In 23 patients with acoustic neurinomas, 16 cases presented thickened acoustic nerve, extending toward internal auditory canal, which was characteristic for this tumor. Trigeminal neurinomas in 4 patients strode over middle and posterior brain fossa mimicking dumbbell. In 3 patients with meningiomas, 1 case presented menigeal tail sign on enhancement. Ependymoma in 1 patient presented subround shape and had a close relation with the outlet of the fourth ventricle. Arachnoid cyst in 1 patient presented smooth edge and had a intensity similar to cerebrospinal fluid. Cholesteatoma in 1 patient presented smooth edge, homogeneous intensity running along pontil cistern. Cavernous hemangioma in 1 patient had no specific signs. The accuracy rates of location and qualitative diagnosis in all patients before operation were 100% and 91.2%. Conclusion MRI is the top choice for detecting tumors in cerebellopontine angle, playing an important role in diagnosis and differential diagnosis.