The presence of fluid in the mastoid air cells does not automatically make the diagnosis of mastoiditis. If there is absence of bony destruction on CT (or other complications), the diagnosis is impossible to make. On MRI, the presence of fluid in the mastoid air cells should be accompanied by mucosal enhancement and/or diffusion restriction is required. The presence of extramastoid change (in this case the soft tissue enhancement at the tip of the mastoid process) is also a helpful adjunct in making the diagnosis.