CT densitometry of the cochlear capsule in otosclerosis.

Cochlear otosclerosis can be recognized in most cases by high-definition axial and coronal CT images. However, routine technique does not allow a quantitative measurement of the changes. Reported here is a study of cochlear CT densitometry. The densitometric profile of the cochlear capsule was obtained in 10 ears with normal hearing and 50 ears in 27 patients with known clinical otosclerosis and progressive mixed-type hearing loss. Patients with hearing loss had decreased absorption of as much as 60% in comparison to the normal range. In 42 ears with abnormal densitometric profiles, the changes were visibly apparent on the CT images, whereas in eight others, the densitometric profile alone demonstrated decreased absorption.