Is MRI Indicated in the Workup of Olfactory Loss?

Objective To understand the utility and cost‐effectiveness of magnetic resonance imaging (MRI) in the evaluation of patients with postviral and idiopathic olfactory loss. Method A retrospective review of consecutive patients presenting with olfactory disorders at a university‐based taste and smell center from July 1998 through October 2011 was performed in an attempt to identify patients with postviral and idiopathic olfactory loss and to determine the diagnostic utility of MRI in their evaluation. Results Eight hundred thirty‐nine patients (average age 53 years, 62% female gender) presented with olfactory loss with a mean University of Pennsylvania Smell Identification Test (UPSIT) score of 21.0. The most common etiologies were postviral (27%), obstructive (13%), traumatic (10%), and idiopathic (29%) olfactory loss. MRI was used in the evaluation of idiopathic and postviral loss 54.9% and 26.4% of the time, respectively, and abnormalities were identified in 4.6% and 3.4% of patients. However, only 2.3% and 1.7% of patients had olfactory loss attributable to imaging abnormalities on MRI. Conclusion The most commonly identifiable etiology of olfactory loss in this series was viral infection; the cause often remained unknown. Brain MRI, though frequently performed, demonstrated a very low diagnostic yield. Based on these data, we recommend against the routine use of MRI in patients with idiopathic and postviral olfactory loss.