Evaluation of Clearance Function of the Eustachian Tube by Sequential Contrast CT

Abstract

Comparisons of Eustachian tube (ET) functions studied by sequential contrast computerized tomography (CT) and by tubotympanic aerodynamics (TTAG) were made. ET clearance function was assessed by the shape of the cartilaginous portion before, during and at the end of swallowing; ventilatory function was studied by TTAG. ET clarity, real-time dynamics and resolution were all better when observed with sequential CT. Contrast medium was instilled into the middle ear via a drumhead perforation and 1 scan/sec taken during swallowing. We classified ET function based on the presence or absence of a) movement of the cartilaginous portion, and b) contrast medium in the ET as i) movement present, contrast medium seen in ET; ii) movement absent, contrast medium present in ET; and iii) movement present, no contrast medium in the ET. Ventilatory and clearance functions did not parallel one another, attributable to some mechanical differences between the two functions.

Key Words:

• eustachian tube
• sequential CT
• ET function