涉及颅底咽旁间隙肿瘤的CT及MRI影像学特征

Imaging characteristics of CT,MRI of tumors involving skull base in the parapharyngeal space

目的:探讨涉及颅底咽旁间隙肿瘤的CT、MRI影像学特征,提高颅底咽旁间隙肿瘤的诊断率。方法:回顾性分析经病理确诊的31例涉及颅底咽旁间隙肿瘤患者的CT、MRI影像学特征,重点研究肿瘤的形态、肿瘤与周围组织的关系、CT所显示的密度大小以及MRI显示的信号高低。结果:31例中,神经鞘瘤19例、涎腺混合瘤8例、颈动脉体瘤2例、鼻咽癌颅底咽旁间隙转移2例。神经鞘瘤与涎腺混合瘤均可表现为圆形或椭圆形、边界光滑、包膜完整的肿块;多形性腺瘤均来源于腮腺深叶;神经鞘瘤的肿块与腮腺深叶分界清楚,对同侧鼻咽腔、口咽腔受压的影响,与肿瘤的大小、位置有关。颈动脉体瘤CT、MRI显示软组织肿块,形状多较规则,CT平扫皆呈等密度软组织肿块,增强扫描肿块明显强化;MRI扫描,T1WI呈等或稍高于周围肌肉的信号,T2WI为不均性高信号,内可见流空血管影像。鼻咽癌颅底咽旁间隙转移MRI显示T1WI椭圆形肿物低密度信号,T1WI增强扫描后可见肿块高信号内有坏死囊变区。结论:涉及颅底咽旁间隙肿瘤皆有CT、MRI影像学特征,正确认识这些特征有助于临床早期诊断,减少误诊,为制订手术方案提供重要的参考依据。

Objective:To discuss imaging characteristics of CT,MRI of tumors involving skull base in the parapharyngeal space,maximatily limit and improve the diagnosis rate of tumors involving skull base in the parapharyngeal space.Method:Thirty-one patients with tumors involving skull base in the parapharyngeal space treated in our department were collected and reviewed.All the patients have pathological diagnosis and were examined by CT and/or MRI.To explore shape of tumor,its relation with surrounding structures,CT shows density size and the MRI signal directly through retrospective analysis of imaging characteristics of CT,MRI.Result:In all the 31 cases,19 tumors were schwannoma,8 tumors were mixed tumor of salivary gland,2 tumors were carotid body tumor,2 tumors were nasopharyngeal darcinoma involving skull base.Schwannomas and saliary gland mixed tumor can be expressed as round or oval with periphery smooth,and had intact capsule.The tumors had necrosis,sac variable area.Pleomorphic adenoma are all derived from deep parotid.Schwannoma had clear boundary with deep parotid.The effect of cavum nasopharyngeum and cavum oropharyngeum is relevant to tumor sizes and locations.Imaging characteristics of CT,MRI for carotid body tumor show soft tissue mass with attenuation similar to that of muscle.CT enhancement scan show intense enhancement.MRI show imaging of flowing empty vein.Imaging characteristics of MRI for nasopharyngeal darcinoma involving skull base in the parapharyngeal space show oval mass with low density signal,T1WI enhancement scan show necrosis,sac variable area.Conclusion:CT and MRI could provide the position,size,boundry of the tumor and its relationship with cervical blood vessels well,which were important to operation schemes.CT and MRI before operation are valuable to the treatment of PPS tumors.