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

Abstract

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. Key words: Ear,middle; Ear neoplasms; Jugular foramen; Diagnostic imaging