Emergency radiologic approach to mastoid air cell fluid.

Mastoid air cell fluid is a commonly seen, but often dismissed finding. Given the location of the mastoid portion of the temporal bone and its location adjacent to vital structures, a careful evaluation is important for the emergency radiologist. While occasionally benign, fluid within the mastoid air cells can be an early sign of more severe pathology, and familiarity of regional anatomy allows for early identification of disease spread. This article describes the important anatomy, the common pathologies, and a radiologic approach to assessing the mastoid air cells in order to guide referring clinicians.