Incidental paranasal sinus abnormalities on MRI of the brain.

T2-weighted magnetic resonance imaging (MRI) presents paranasal sinus pathology with remarkable clarity. However, it has yet to be demonstrated that all MRI findings represent true pathology and not minor or incidental findings of no consequence. In an effort to resolve this question, we have analysed retrospectively 263 consecutive T2-weighted MRI examinations of the head performed for indications not associated with possible sinus pathology. We examined these studies for abnormally increased signal in the paranasal sinuses and the sites of involvement. Mucoperiosteal thickening, mucus retention cysts, air-fluid levels or total sinus opacification were recorded. Of the 263 studies examined, 65 (24.7%) demonstrated abnormalities in the paranasal sinuses. We conclude that because of its great sensitivity MRI will often detect abnormalities in the paranasal sinuses which are unrelated to the patients' presenting problems.