Is mastoiditis being over-diagnosed on computed tomography imaging? —radiological versus clinical findings

Abstract

Background: Non-contrast computed tomography (CT) of the mastoid air cells in the temporal bone is a standard investigation for patients with suspected coalescent mastoiditis. Mastoid air cell opacification on a CT imaging without bony erosion has been notably diagnosed as mastoiditis which can prompt concern from the requesting practitioner and potentially lead to escalation of care. This analysis aims to determine the relationship between a radiological reporting of mastoiditis and the clinical diagnosis of acute mastoiditis. Methods: A retrospective review of 1,946 CT scans undertaken across three sites were performed. Results: Fifty-two patients had CT reported mastoiditis. Thirty patients (57.7%) had imaging to investigate the presence of acute otological symptoms. The clinical diagnosis of acute mastoiditis was made in 3 of these cases (5.8%). Ten patients (19.2%) had a final diagnosis of Otitis Media. Nine patients (17.3%) had a final diagnosis of otitis externa. Three patients (5.8%) had investigation for acute hearing loss. Three patients (5.8%) had a diagnosis of trauma. Two patients (3.8%) had a diagnosis of exostosis without significant infection. The other twenty-two patients (42.3%) were asymptomatic from an otological perspective and the mastoid opacification was seemingly an incidental finding. In all, 11.5% of patients with a finding of mastoiditis on CT imaging required intravenous (IV) antibiotic therapy, 3 (5.8%) with diagnosed acute coalescent mastoiditis, 2 with severe otitis externa. Conclusions: Mastoiditis determined on CT imaging has a poor correlation with the clinical diagnosis and is seen in many incidental patients or alternative pathologies. It is suggested that without evidence of bony erosion that this finding may preferentially reported as mastoid opacification only, for further clinical correlation.