Applications of Magnetic Resonance Imaging in Adult Temporal Bone Disorders

Magnetic resonance imaging is the primary imaging modality for evaluation of the nonosseous components of the adult temporal bone. Both temporal bones are always imaged to compare sides and the brain/skull base included so that intracranial extension can be evaluated. Middle ear congenital cholesteatoma presents as a nodular soft tissue mass, without osseous erosions or involvement of Prussak space, and with normal pars flaccida. A non–echo planar (EP) diffusion-weighted (DW) imaging sequence should be preferred rather than an EP DW imaging sequence because it is less sensitive to susceptibility artifacts and is therefore able to show cholesteatomas as small as 2 mm. In early stages of necrotizing external otitis, nonspecific soft tissue swelling is present in the external auditory canal with erosion at the petrotympanic fissure and obliteration of the retrocondylar fat pad.