Imaging of Temporal Bone.

Multidetector computed tomography has been the benchmark for visualizing bony changes of the ear, but has recently been challenged by cone-beam computed tomography. In both methods, all inner ear bony structures can be visualized satisfactorily with 2D or 3D imaging. Both methods produce ionizing radiation and induce adverse health effects, especially among children. In 3T magnetic resonance imaging, the soft tissue can be imaged accurately. Use of gadolinium chelate (GdC) as a contrast agent allows the partition of fluid spaces to be visualized, such as the bulging of basilar and Reissner's membranes. Both intravenous and intratympanic administration of GdC has been used. The development of positive endolymph imaging method, which visualizes endolymph as a bright signal, and the use of image subtraction seems to allow more easily interpretable images. This long-awaited possibility of diagnosing endolymphatic hydrops in living human subjects has enabled the definition of Hydropic Ear Disease, encompassing typical Meniere's disease as well as its monosymptomatic variants and secondary conditions of endolymphatic hydrops. The next challenge in imaging of the temporal bone is to perform imaging at the cellular and molecular levels. This chapter provides an overview of current temporal bone imaging methods and a review of emerging concepts in temporal bone imaging technology.