颅底软骨瘤的CT及MRI征象分析

CT and MRI features analysis of chondroma at skull base

目的分析颅底软骨瘤的CT和MRI影像征象。方法回顾性分析经病理组织学证实的7例软骨瘤的CT、MRI影像学特点。7例均行MRI平扫及增强检查,其中5例行CT平扫及增强检查。结果肿瘤均位于颅底中线旁硬膜外,分别为鞍旁4例、颈静脉孔区2例及后颅窝底1例。颅底软骨瘤呈分叶状5例,类圆形及哑铃状各1例。周围骨质多为膨胀性破坏(n=5)。CT平扫为等高及高低混杂密度影,瘤内均可见钙化,其中4例为大量形态各异钙化,1例为少量颗粒状钙化;增强扫描呈无明显强化(n=4)及轻度不均匀强化(n=1)。MR平扫5例T1WI呈不均匀低信号、T2WI高低混杂信号,增强扫描表现为周边及内部分隔中度强化,呈蜂窝状改变;2例平扫T1WI呈均匀低信号、T2WI均匀高信号,增强扫描较均匀延迟强化。结论颅底软骨瘤好发于颅底中线旁的硬膜外,特别是鞍旁及蝶岩骨交界区;CT及MRI表现有一定特点,尤其CT对定性诊断有重要价值,两种检查方法联合应用可提高术前诊断准确率。

Objective To analyze CT and MR/features of chondroma at skull base. Methods CT and MRI findings of seven cases of chondroma at skull base proved by histopathology were retrospectively analyzed. Plain and enhanced MRI scanning were performed in all the patients, and plain and enhanced CT scanning were performed in 5 cases. Results The ~rnors were located in the middle skull base beside subdural, with 4 cases in the parasellar, 2 cas- es in the jugular foramen area, and 1 case in the midline area of the posterior fossa. 5 cases of skull base chondroma were lobulated, 1 case showed class round, and 1 case are dumbbell-shaped. Expansion bone destruction was showed in most cases （5 cases）. Plain CT showed the contours and mixed high and low density shadow. Calcification shadow can be seen in all the cases, there were large number of different patterns of calcification in 4 cases and small amount of granular calcification in 1 case. Enhanced CT showed no strengthening in 4 cases, and uneven reinforcement in I case. Uneven low signal on T^WI and high mixed low signal on T^WI were displayed in 5 cases in plain MRI, they showed peripheral and internal separated moderate strengthening in enhanced MR/, like honeycomb. Uniform low sig- nal on T^W/and uniform high signal on T^WI were showed in 2 cases, which showed uniformly delayed enhancement in enhanced MR/. Conclusion Most of skull base chondromas are located in the middle skull base beside subdural, especially butterfly rock saddle paraneoplastic bone junction area. CT and MRI features have certain characteristics, especially CT has important value in qualitative diagnosis. The combined application of the two methods can improve preoperative diagnostic accuracy.