MRI of mastoid and middle ear disease

MR and CT are complementary studies in evaluating inflammatory disease or neoplasms of the mastoid and middle ear cavities. CT should be performed prior to MR in the evaluation of patients with primary temporal bone pathology because of its ability to detect and delineate both soft tissue and bony abnormalities. CT should be performed whenever intratympanic or facial nerve pathology is suspected, even if the MR examination is normal. MR can be used to further characterize tympanic cavity masses as effusion, glomus tumor, hemorrhage or cholesterol granuloma. The prospect of Gd-DTPA-enhanced MR promises increased sophistication in the detection of glomus tumors and facial nerve neuromas. Noncontrast MR cannot differentiate between cholesteatoma and granulation tissue. The efficacy of Gd-DTPA in inflammatory disease of the temporal bone awaits further investigation.