CT imaging of the eustachian tube using focal contrast medium administration: a feasibility study

Abstract

Objectives: We aim to develop an imaging technique for visualization of the Eustachian tube (ET) lumen. Study Design: A prospective, experimental study in an animal model and in human cadaver specimens. Methods: Applying iodixanol to the middle ear in two human temporal bone specimens, followed by computed tomography (CT) examinations, we optimized contrast dilution, CT algorithm, and head positioning for visualization of contrast passage through the ET. Myringotomy was performed on eight rabbits. Based on the cadaver study, a 20% iodixanol solution was applied to the middle ear, and subsequent CT scans were performed to observe iodixanol in the epipharynx. For some animals, the procedure was repeated on the contralateral ear. We performed the procedure twice on four subjects. Twenty examinations were included. Iodixanol appearance in the ET and the epipharyngeal orifice was assessed qualitatively on CT scans. The tympanic membrane was inspected after 1 or 2 weeks, and histopathological examination of six contrast-exposed temporal bones was performed. Results: The cadaver study provided information on imaging technique and contrast dosage. In rabbits, iodixanol passed through the ET in 19 of the 20 ears. Qualitatively, optimal visualization was seen after 9 to 12 minutes. Clinical inspection after 1 or 2 weeks revealed normal middle ear status. Histopathological samples showed no sign of inflammatory reaction in the tympanic membrane, middle ear, or ET. Conclusion: Iodixanol application to the middle ear is feasible, safe, and demonstrates patency of the ET