The Prevalence of Incidental Mastoid Opacification and the Need for Intervention: A Meta-Analysis

The increasing use of cross-sectional imaging has led to the predicament of incidental mastoid opacification (IMO). We investigated the prevalence of IMO and the clinical need for ENT assessment or intervention when identified.

Systematic review and meta-analysis.

The PRISMA statement standards were used to search electronic databases including Medline, Embase, PubMed, and Web of Science. The selection criteria were mastoid opacification found on computed tomography (CT) or magnetic resonance imaging (MRI) as incidental findings.

A total of 16 studies were identified for qualitative analysis and 15 for quantitative analysis, mainly retrospective. The pooled prevalence of IMO in 246,288 patients was 8.4% (95% CI 5.5-12.0). The prevalence of IMO was significantly higher in studies with children (17.2%, 95% CI 10.9-24.6) than those with adults (6.1%, 95% CI 3.3-9.6); smaller sample size studies (12.4%, 95% CI 8.1-17.3) compared to larger sample size studies (4.1%, 95% CI 1.5-7.8); and when IMO was detected by viewing images (14.5%, 95% CI 9.9-19.8) compared to reading reports (3.5%, 95% CI 1.3-6.6). Imaging modality was not a significant moderator due to similar IMO rate on CT (8.6%, 95% CI 1.8-19.7) and MRI (10.4%, 95% CI 4.9-17.6). Nine studies reported on clinical outcomes of patients with IMO, and none reliably reported any cases of clinical mastoiditis.

The term "mastoiditis" on radiology reports based on IMO does not indicate a clinical diagnosis of mastoiditis, although the current body of evidence is limited. Otolaryngology review is suggested if clinical correlation detects otological signs or symptoms.

NA Laryngoscope, 132:422-432, 2022.