CT与MRI在颅底软骨肉瘤诊断中的应用价值

目的分析颅底软骨肉瘤的CT和MRI影像征象，探讨两种检查方法在颅底软骨肉瘤诊断中的价值。方法回顾性分析经病理组织学证实的8例软骨肉瘤的CT、MRI影像学特点。本组中8例均行CT平扫及增强扫描检查，6例行MRI平扫及增强扫描。结果病灶均位于颅底中线旁的硬膜外，其中鞍旁4例、颈静脉孔区2例、前颅窝底及后颅窝底各1例。病变呈分叶状7例，呈类圆形1例。周围骨质呈溶骨性破坏6例，膨胀性破坏1例，侵蚀性破坏1例。CT平扫密度不均匀，瘤内可见形态不一钙化，多呈稀疏散在分布（6例），大部分钙化灶边缘较模糊；增强扫描轻度至中度不均匀强化。MR信号不均匀，平扫T1WI呈不均匀低信号，T2wI呈高低混杂信号，增强扫描4例表现为周边及内部分隔中度强化，呈花环状或蜂窝状强化改变（病理类型为高分化型软骨肉瘤Ⅰ～Ⅱ级），2例呈不均匀斑片状明显强化（高分化型Ⅲ级及间叶性软骨肉瘤）。结论颅底软骨肉瘤好发于颅底中线旁，CT可以清晰显示瘤内特征性的钙化及周围骨质破坏征象，MRI增强扫描强化特点有助于判断肿瘤恶性程度，两者结合有利于该病的诊断。

Application of CT and MRI in the diagnosis of chondrosarcoma

Objective To analyze the CT and MRI imaging features of skull base chondrosarcoma and to discuss the val- ue of this two methods in the diagnosis of chondrosarcoma. Methods 8 cases of CT and MR images were reviewed retro- spectively in chondrosarcomas confirmed by biopsy. Plain and enhanced CT scanning were performed in all of the cases, and plain and enhanced MRI scanning were performed in 6 cases. Results All of the cases were located in the middle skull base beside by epidural： 4 cases in the parasellar region, 2 cases in the jugular foramen region, 1 case in the posterior cra- nial fossa and 1 case in the anterior cranial fossa. 7 cases of the tumor were lohulated, and 1 case was oval. 6 cases showed dissovle bone destruction, 1 case showed expansile bone destruction and 1 case showed rodent bone destruction. Plain CT scan showed tumors uneven density, all of cases had different shape calcification which was given priority to sparse distri- bution within the tumor （6 cases）. Most of the calcification showed fuzzy edges. Enhanced CT scanning showed mild to moderate uneven reinforcement. MR signal of the tumors were uneven, it showed uneven low signal on T1WI and hetero- geneous hyper-intensity on T2WI. Enhanced MRI scanning showed periphery and internal division moderate enhancement as flower ring or honeycomb shape in 4 cases （pathological type was highly differentiated grade Ⅰ～Ⅲ chondrosarcoma）, and uneven patchy obvious enhancement in 2 cases （highly differentiated grade III and mesenchimal chondrosarcoma）. Conclusion Skull base chondrosarcoma is located in the middle skull base beside by epidural. CT could clearly display the characteristic signs of intratumoral calcification and signs of bone destruction around. The signal characteristics of MRI en- hancement scanning may help determine the malignant degree of the tumor. The combination of CT with MRI is conducive to the diagnosis of this disease.