Magnetic resonance imaging is the ‘gold standard’ for screening patients suspected to have acoustic neuroma. Various abnormalities are picked up through this investigation, one of which, not uncommonly reported, is mastoiditis. This requires referral to otolaryngology and further evaluation.

In the presented series, comprising 500 patients who underwent MRI for reasons other than chronic ear disease, 5.8% were reported to have mastoiditis. The patients with mastoiditis constituted 39.7% of all abnormalities reported. None of these patients had clinical evidence of middle ear disease.

This required further referral and cost an additional £4350. The authors quote other studies in which mastoiditis has been reported more often in patients undergoing MRI screening for other purposes. One study has reported that, as often used, intramastoid T2 hyperintensity alone is not a reliable sign for acute mastoiditis and in fact the intramastoid intensity signal is hypo-intense compared to cerebrospinal fluid and there is an absence of diffusion restriction and intense intramastoid enhancement in ‘incidental’ mastoid effusion. A revision of guidelines is therefore required to avoid unnecessary referrals and attendant worries for the patients.

Incidental mastoiditis in magnetic resonance imaging scans: clinical relevance and cost implications.
Abbas Y, Yeun HS, Trinidade A, Watters G.
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Madhup K Chaurasia

Mid and South Essex NHS Foundation Trust, UK.

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