Incidental mastoiditis on magnetic resonance imaging scans: clinical relevance and cost implications

Abstract

ObjectivesTo determine: (1) the incidence of incidental ‘mastoiditis’ reported on magnetic resonance imaging scans performed in patients with asymmetrical sensorineural hearing loss and/or unilateral tinnitus; (2) how many of those patients have actual otological pathology and/or require treatment; and (3) the financial implications of such a reporting practice.MethodRetrospective case series.ResultsBetween October 2015 and November 2016, 500 patients underwent magnetic resonance imaging of the internal auditory meatus to rule out cerebellopontine angle lesions. There was an incidental finding of increased mastoid signalling in 5.8 per cent (n= 29), of which 20.7 per cent (6 of 29) were reported as bilateral cases. The diagnosis of ‘mastoiditis’ was found in 39.7 per cent (29 of 73). None of these patients had any pathology identified clinically. Other significant pathology was identified in a further 8.8 per cent (n= 44).ConclusionThe diagnosis of mastoiditis is primarily clinical. An incidental finding of high signalling in the mastoid region on magnetic resonance imaging is highly unlikely to represent actual clinical disease. In patients who are scanned for other reasons and who do not complain of otological symptoms, such findings are unlikely to require otolaryngology input.

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

“…The pooled prevalence of IMO on CT 22–25 and MRI 10,11,20,21,26–31 were similar at 8.6% (95% CI 1.8–19.7) and 10.4% (95% CI 4.9–17.6), respectively, as shown in Figure 4. Imaging modality was not found to be a significant moderator (QM (1) = 0.12, P = .73).…”

“…Sample size. Dividing the studies into sample sizes of less than 11,20,22,24,26,[28][29][30][31] or greater than 1000 10,12,21,23,25,27 demonstrated a small negative regression coefficient (À0.2; Z (13) = À2.9, P = .003), as shown in supplementary file 6. The pooled prevalence in smaller studies was 12.4% (95% CI 8.1-17.3), compared to 4.1% (95% CI 1.5-7.8) in larger studies, as shown in Figure 6.…”

“…Some authors report that the presence of incidental mastoid opacification (IMO) allows detection of otomastoiditis, 10 while others regard this finding as a clinically insignificant entity and suggest ENT input in not required. 11,12 A radiological diagnosis of mastoiditis can lead to unnecessary escalation of treatment with intravenous antibiotics. 12 This has a direct implication on healthcare resources and cost, 12 as well as patient exposure to potential adverse events associated with the sequelae of a prolonged hospital stay and medical interventions.…”

Incidental finding of mastoid opacification in computed tomography imaging of the asymptomatic paediatric population

“…Abbas et al . conducted a retrospective case series evaluating radiological mastoid opacification on MRI scans in the adult population, and showed an incidence of 5.8 per cent 18 . Wilkinson et al .…”

“…The opacification of mastoid air cells is a commonly reported radiological finding, and patients are often erroneously diagnosed with acute mastoiditis when this finding is present, despite the absence of the characteristic clinical findings. This issue has been previously studied by examining incidental findings on magnetic resonance imaging (MRI) in children 14 – 18 and on CT in the adult population 19 . To the authors’ knowledge, CT findings in the paediatric population have not been studied.…”