累及咽旁间隙的颅底软骨肉瘤的CT和MRI诊断

CT and MRI diagnosis of skull base chondrosarcoma extensively involving parapharyngeal space

目的:探讨CT、MRI对累及咽旁间隙的颅底软骨肉瘤的诊断价值。方法:回顾性分析6例经病理证实的累及咽旁间隙的颅底软骨肉瘤患者的CT、MRI资料,其中3例为黏液样软骨肉瘤。结果:6例均广泛累及咽旁间隙,侵犯颈静脉孔5例、岩尖3例、寰椎旁3例。主要CT表现为软组织肿块伴不规则骨质破坏,肿块呈分叶状4例,类圆形2例,伴不同程度点状、斑片状及周边弧形钙化;4例CT增强扫描呈轻度不均匀强化。MRI T1WI示肿块呈低或稍低信号,T2WI上呈多房分叶状明显高信号,内有低信号分隔,其中3例黏液样软骨肉瘤信号较均匀,其余信号不均匀,有片状等或稍高信号灶。增强扫描呈轻度不均匀强化,伴周边及间隔强化。结论:颅底软骨肉瘤可广泛累及咽旁间隙,易造成误诊;CT可显示钙化及骨质破坏,MRI上肿块信号特点及强化方式有一定特点,两种检查方法联合应用可减少误诊。

Objective：To discuss the value of CT and MRI in the diagnosis of skull base chondrosarcoma extensively involving parapharyngeal space. Methods： CT and MRI images of six patients with pathology confirmed skull base chondro- sarcoma extensively involving parapharyngeal space were analyzed retrospectively. Of these, 3 cases were myxoid chondro- sarcoma. Results： Tumor extensively invaded parapharyngeal space were showed in all the six patients,including jugular fo ramen in 5 cases,petrous apex in 3 cases and paravertebral tissue of atlas in 3 cases. Soft tissue mass and irregular bone de- struction were found on CT. The mass were lobular in shape （4 cases） or oval in shape （2 cases） ,accompanied with spotty, patchy and peripheral curvilinear calcifications. Four cases with enhanced CT scan showed mild and heterogeneous enhance- ment. On MRI, tumors showed hypo or slightly hypo-intensity on T1 WI, marked hyper-intensity with hypo-intensed septa on T2 WI. The signal intensity was homogeneous in the 3 cases with myxoid chondrosarcoma and the rest showed heteroge- neous with patchy iso- or slightly hyper-intensities. After contrast administration,mild heterogeneous enhancement accom- panied with peripheral enhancement of the septa could be seen on MRI. Conclusion： Chondrosarcoma of skull base may extensively invade parapharyngeal space, which might easily lead to misdiagnosis. Intra-tumoral calcifications and bone destruction could be displayed on CT and certain characteristic MRI signal and enhancement patterns could be showed. Reduc tion of mis diagnosis could be achieved by using CT in combination with MRI.