侵及颈静脉孔区的原发性中耳癌的CT、MRI诊断

目的 探讨侵及颈静脉孔区的原发性中耳癌的CT、MRI特点.方法 回顾性分析7例经手术病理证实的侵及颈静脉孔区原发性中耳癌患者的CT、MRI资料,其中6例行高分辨率CT(HRCT)扫描,1例行常规CT增强扫描,7例均行MR平扫+增强.结果 HRCT显示鼓室、鼓窦、外耳道深部及颈静脉孔区软组织病灶伴不规则虫蚀样骨质破坏,涉及颈静脉孔(7例)、咽鼓管骨性段(7例)、面神经管(4例)、颈动脉管(4例)、外耳道前后壁(3例)、听小骨(2例)及前庭窗、水平半规管(1例)等结构的破坏.4例病变密度较均匀,CT值约30～55 HU,2例肿块内见少许小片状高密度影.1例CT增强显示中度较均匀强化.MR平扫示边界不清软组织肿块,与脑灰质相比,T1WI呈等、略低信号,T2WI呈等、略高信号,其中5例信号较均匀,2例肿块内见少许小片状T1WI、T2WI低信号灶,增强扫描5例呈中度较均匀强化,2例不均匀强化,内见小片状无强化区.MRI显示4例侵及颈内动脉,1例侵及乙状窦.结论 原发性中耳癌可广泛侵及颈静脉孔区,易造成误诊.HRCT可准确显示中耳癌骨质破坏特点及范围,咽鼓管骨性段破坏可帮助减少误诊；MRI能更清楚显示病变范围,肿瘤信号及强化方式有一定特点.

CT and MRI diagnosis of primary middle ear carcinoma invading jugular foramen

Objective To study the CT and MRI features of primary middle ear carcinoma invading jugular foramen.Methods CT and MRI images of 7 patients with surgically and pathologically confirmed primary middle ear carcinoma invading jugular foramen were analyzed retrospectively,including high resolution CT (HRCT) scan in 6 cases,CT enhancement scan in 1 case and MR plain and enhancement scan in 7 cases.Results On HRCT,the soft tissue lesions mainly located in tympanum,tympanic sinus,the deep of external auditory canal and jugular foramen,and irregular “moth-eaten” bone destruction could be seen,including the destruction of jugular foramen in 7 cases,eustachian tube in 7 cases,facial nerve canal in 4 cases,carotid artery canal in 4 cases,external auditory canal wall in 3 cases,auditory ossicles in 2 cases,vestibular window and horizontal semicircular canal in 1 case.CT plain scan showed the density of soft tissue mass was uniform in 4 cases with CT value of 30-55 HU,and heterogeneous in 2 cases,in which small pieces high density lesions could be found.CT enhancement scan in 1 case revealed moderate and homogeneous enhancement.On MR plain scan,the soft tissue masses with hazy margins could be seen,and compared to the gray matter of brain,the lesions were isointense or slightly hypointense on T1 WI and isointense or slightly hyperintense on T2 WI.The signal was homogeneous in 5 cases and inhomogeneous in 2 cases with small pieces of hypointensity both on T1WI and T2WI.After enhancement,the lesions were enhanced moderately and homogeneously in 5 cases and inhomogeneously in 2 cases with small pieces of nonenhanced area.MRI also showed the erosion of carotid artery in 4 cases,sigmoid sinus in 1 case.Conclusion The primary middle ear carcinoma can invade the jugular foramen area extensively,which may lead to misdiagnosis.HRCT can precisely depict the bone destruction and the invasion of the important anatomic structures in the primary middle ear carcinoma,and the destruction of eustachian tube can help to reduce misdiagnosis.MRI can more clearly show the extent of tumor and the mass signal and enhancement pattern.