面神经瘤的影像学研究

目的：研究面神经瘤的影像学检查方法和影像学表现，提高诊断准确性。方法：10例经手术病理证实的面神经瘤均行CT检查，6例还进行MR平扫和增强扫描。回顾性分析CT表现和MRI表现，并比较CT和MRI的优缺点。结果：10例面神经瘤中6例面神经鞘瘤和4例面神经纤维瘤，8例累及面神经水平段，6例累及膝部，4例累及乳突段，2例累及迷路段，3例累及内听道段，2例累及腮腺段，1例累及脑池段。主要CT表现：面神经管扩大9例；鼓室内软组织影7例；听小骨破坏5例；乳突蜂房内软组织肿块4例。主要MRI表现：6例均表现面神经增粗，其中2例显示鼓室内=乳突内和颈静脉窝软组织肿块，2例显示鼓室内软组织肿块；3例肿块呈略长T1、略长T2信号，信号不均匀，增强后呈不均匀强化；3例肿块与面神经呈等信号，信号均匀，呈均匀强化；2例面神经瘤累及内听道段面神经，平扫未显示，增强后呈明显强化而显示。比较CT与MRI表现后，发现2例累及面神经内听道段者MRI显示而CT未显示，1例累及面神经鼓室段起始部者MRI亦显示而CT未显示；对于较小的面神经瘤，MRI能直接显示增粗的面神经本身，而CT仅显示面神经管扩大和（或）破坏。结论：CT和MRI，尤其是MR增强扫描能很好地显示面神经瘤的形态、部位、范围和内部结构，有助于定位诊断和定性诊断，为临床制订手术方案和确定手术入路提供依据。

Imaging investigation of facial neuroma

Objective To investigate imaging methods and imaging findings of facial neuroma to promote its diagnostic accuracy. Methods CT was performed in all 10 patients with facial neuroma confirmed by pathology and surgery. Of all 10 patients, plain and enhanced MRI was performed in 6 patients. CT and MRI findings were analysed and compared retrospectively. Results Ten facial neuromas consisted of 6 schwannoma and 4 neurofibroma. The tumor affected the horizontal segment of facial nerve in 8 cases, anterior genu in 6, mastoid segment in 4, labyrinth segment in 2, internal auditory canal segment in 3, intraparotid segment in 2, and cistern segment in 1. On CT, enlargement of fallopian canal was seen in 9 cases, soft tissue mass in tympanum in 7 cases, destruction of auditory ossicles in 5, and bone destruction with soft tissue mass in mastoid region in 4. MRI demonstrated enlargement of facial nerve in 6 cases, soft tissue mass in tympanum, mastoid region and jugular fossa in 2, and soft tissue mass only in tympanum in 2. In 3 of 6 patients, the soft tissue mass was slightly hypointense and inhomogeneous on T 1WI, hyperintense on T 2WI and heterogeneous enhancement after administration of contrast medium. However, in other 3 cases, the soft tissue mass showed isointense signal on T 1 and T 2 weighted images and homogeneous enhancement after contrast. 2 neuroma involving internal auditory canal segment of facial nerve was clearly demonstrated on postcontrast T 1WI but not shown on pre contrast T 1 and T 2 images. CT missed 3 neuromas found with MRI, 2 involving internal auditory canal segment and 1 involving tympanum segment. For the small facial neuroma, CT found enlargment and/or destruction of fallopian canal only, but MRI could demonstrated enlarged facial nerve itself. Conclusion CT and MRI, especially postcontrast T 1WI, can accurately display shape, location, extension, and structure of facial neuroma, which contribute to diagnose the lesion and provide evidence for surgical planning.