The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion. Imaging studies most commonly used for the temporal bone are CT, MRI, and arteriography. Conventional radiography now used mainly for to assess mastoid and petrous pneumatization or the placement of cochlear implant electrodes. A 20 degree coronal oblique is used for assessment of the oval window, promontory, and tympanic facial canal. Sagittal reconstructions are used for mastoid facial canal and vestibular aqueduct.
Advantages are no ionizing radiation and imaging in any plane without moving the patient's head.
The concentration of the hydrogen nuclei and two magnetic relaxation times, T1 and T2, affects the strength of the MR signal. Fat and body fluids have large quantities of free protons and produce signals of high intensity. Cortical bone and fibrous tissue contain few protons and emit low intensity or no signal. The normal mastoid, EAC, and ME are dark because air emits no signal. Fluid in the IAC and inner ear structures are the only signal emitting structures in the petrous pyramid.