MRI平扫加增强检查对微型、小型听神经瘤的诊断价值

目的评价增强MRI对微型、小型听神经瘤的诊断价值。材料和方法本文收集了经手术和病理证实的微型听神经瘤13例（d≤10mm），小型听神经瘤19例（10〈d≤20mm），男15例，女17例，年龄33—61岁，平均41．8岁，采用SignaHDX3．OTMRI超导型MR系统平扫及增强扫描，对其影像学表现进行回顾性分析，对肿瘤病灶边缘、信号、邻近结构关系进行比较。结果32例微、小型听神经瘤Gd—DTPA扫描呈明显强化，病灶的位置．边缘及邻近结构关系更明确。肿瘤Tl加权序列为等或稍低信号，T2加权序列为高信号或稍高混杂信号，内听道均未见扩大。11例病灶局限在到内听道内，肿瘤直径约0．3—1．2mm，平均0．54mm；3例肿瘤位于听神经，T1WI，T2WI听神经稍增粗、未见异常信号，增强扫描后呈点片状强化，18例肿瘤大部分位于内听道内，其肿瘤少部分突入桥小脑角肿瘤直径约0．8—2．0mm，平均1．24mm。结论MRI平扫＋增强是防止微型、小型听神经瘤漏诊最有效方法，其诊断准确、可靠。

Diagnostic Values of Plain and Contrastenhanced MRI to Mini and Small Size Acoustic Neuroma

Objective To evaluate diagnostic values of enhanced MR imaging to mini and small size acoustic neuroma. Materials and methods 13 cases with mini-size acoustic neuroma （ d ~ 10ram ） and 19 cases with small size acoustic neuroma （ 10〈d 〈 20ram ） which were confirmed by surgery and pathology were collected. 15 cases were male and 17 cases were female aged 33-61 years old, average 41.8 years old. Conventional and contrast- enhanced MRI were performed. The images were retrospectively analyzed, and boundaries. signals and adjacengt structures were compared. Results 32 cases with mini and small size acoustic neuroma showed obvious enhancement in Gd-DTPA scanning, and the location, signal, adjacent structures of masses showed more clearly. Masses showed equal or low signal on T1W1, high signal on T2WI. There were no enlargement of offected canal, 11 cases located in internal auditory canal, and the size of tumors were about 0.3-1.2ram, average 0. 54ram. 3cases located in auditory nerve, TIWI and T2WI showed thickened auditory nerves, but no abnormal signals, and the tumors showed flaky enhancement. Tumors of 18 cases were mostly located in internal auditory canal, small parts of them out into cerebellopontine angle, and the size were 0.8-2.0mm, average 1.24mm. Conclusion Con- ventional and contrast-enhanced MRI is the most effective examination to prevent missed diagnosis of mini and small size acoustic neuroma, and tile diagnosis is accurate and reliable.