Chronic otomastoiditis: a conceptual understanding of CT findings.

Inflammation of the middle ear cleft is a disease of great interest from both clinical and radiologic points of view. The attic floor (tympanic diaphragm), the tympanic isthmus, and the aditus ad antrum play important roles in inflammatory processes of the middle ear cleft. The anatomy of the temporal bone at this level was examined by studying microdissections of 250 fresh temporal bones and reviewing over 1,000 high-resolution computed tomography (CT) scans of the temporal bones. The pertinent anatomy is described, and the role of the tympanic diaphragm and isthmus in determining the degree to which middle ear disease may progress is stressed. The appearances on CT scans of chronic otomastoiditis, tympanosclerosis, cholesterol granuloma, attic retraction pocket, and acquired cholesteatoma are reviewed and illustrated.