听神经瘤的MRI诊断
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听神经瘤的MRI诊断

董进 马志娟 (430022武汉市第一医院放射科)

[摘要]目的  研究听神经瘤的MRI表现与特征。方法  通过手术病理对照,回顾分的了38例听神经瘤的MRI表现,其中微小听神经瘤为5例,行Gd-DTPA增强扫描为31例。结果  听神经瘤的MRI表现主要为:(1)肿瘤以内听道为中心生长 ,第Ⅶ、Ⅷ神经束较对侧增粗,与肿瘤主体无明确分界,增强后可见两者相连,颇为特征;(2)肿瘤在T1加权图像上呈低信号,略低信号或低等混合信号,T2加权呈高信号或高等混合信号;(3)注射Gd-DTPA后肿瘤呈均匀、不均匀或环状强化;(4)肿瘤边界清晰,边缘光整;(5)绝大多数肿瘤患侧内听道前后径扩大,深径缩短;(6)微小听神经瘤的MRI表现为第Ⅶ、Ⅷ神经束正常或局部结状增粗,造影后呈结节状或点状增强。结论 MRI是检查听神经瘤的有效方法,Gd-DTPA对微小听神经瘤的诊断很有价值。

  [关键词] 磁共振成像;听神经瘤;诊断

 

MRI diagaois of acoustic neuroma

Dong Jin, Ma zhi juan, Department of Rodiology, The First Hospitol of Wuhan, Wuhan 430022, China [Abtract] Objective To study MRI appearaneces and characteristics of acoustic neuromas . Methods The MRI features along with patholonic findings of 38 patients with acoustic neuruma were analysed retrospectively. There were 5 small acoustic neuromas, 31 cases were Gd-DTPA enhanced. Results MRI appearances of acoustic neuromas were: (1)The turmors growth round the internal auditory canal, the Ⅶ、Ⅷ nerves affected side were thickened than that of opposite side, There was no marked demarcation between the main bodies of the tumors and the affected nerves . The connection between tumors and affeeted nerves could be showed at contrast enhanced imaging. (2) The tumors were of hypo or isohypo intensity on T1 weighted images and hyper or iso-hyper intensity on  T2 weighted images. (3) After Gd-DTPA administration the tumors were homogeneously or inhomogeneously or circularly enhanced.(4)The margins of the tumors were smoth and well delineated. (5) The affected internal auditory canal usually became shorter in depth and larger in posterior-anterior diameter . (6) MRI appearances of micro-acoustic neuromas were that the affected Ⅶ、Ⅷ nerves were normal in size or nodularly thickened and the tumor reveaed nodular or point enhancement at contrast enhanced MRI. Conclusion MRI is an effective method in detecting acoustic neuromas . Gd-DTPA enhancement is very valuable in the diagnosis of microacoustic neuromas

[Key words ] magnetic resonance imaging; acoustic neuroma; diagnosis

听神经瘤是成人后颅窝常见肿瘤之一,MRI不仅对听神经瘤本身结构,而且对临近解剖结构可提供更多的信息,特别是对微小听神经瘤的检出尤为敏感⑴⑵。

1、资料与方法

1.1  一般资料  收集我院2002年10月-2008年12月38例经MRI检查并经手术证实的病例进行分析,男17例,女21例,年龄 16-73岁,平均48.7岁,30岁以上为33例(86.8%),临床症状以耳鸣,听力下降,面部麻木为主,部分患者伴有头痛、视物昏花,偏瘫或步态不稳等。

1.2 设备  采用 0.3TMRI 和1.5T超导MRI扫描机, 31例进行了增强检查,采用Gd-DTPA,按0.1mmol/kg给药,静脉注射后做横断面T1WI。

2、结果

2.1 听神经瘤的MRI表现  见表1及(图1-5)。

2.2  听神经瘤增强MRI 表现  31例听神经瘤静脉注射Gd-DTPA后,24例实质性肿瘤,11例呈均匀强化;13例呈不均匀强化,4例实质和囊肿性并存的肿瘤,3例呈环状强化,囊变坏死区无明显变化。

 

 

 

表1  听神经瘤的MRI表现

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