Rapid diffusion-weighted MRI for the investigation of recurrent temporal bone cholesteatoma.

BACKGROUND: Suspected cholesteatoma recurrence is commonly investigated with magnetic resonance imaging (MRI) of the temporal bone. Non-echo planar diffusion-weighted imaging (non-EP DWI) has become the sequence of choice.

PURPOSE: To assess the agreement between an MRI protocol incorporating both non-EP DWI and contrast-enhanced sequences, and a shortened protocol without contrast-enhanced sequences in the assessment of suspected cholesteatoma recurrence.

MATERIALS AND METHODS: One hundred consecutive MRIs, consisting of T2-weighted, non-EP DWI and pre- and post-contrast T1-weighted sequences, were reviewed by two radiologists at a tertiary referral centre. Agreement between the two protocols was assessment by means of a weighted Cohen kappa coefficient.

RESULTS: We found a near perfect agreement between the two protocols (kappa coefficient with linear weighting 0.98; 95% confidence interval 0.95-1.00). There were two cases in which the two protocols were discordant. In both cases, the lesion measured <3 mm and images were degraded by artefact at the bone-air interface. The shortened protocol without post-contrast sequences yielded a 32% reduction in acquisition time.

CONCLUSION: When non-EP DWI is available, contrast-enhanced sequences can be omitted in the vast majority of cases without compromising diagnostic accuracy. Contrast-enhanced sequences may provide additional value in equivocal cases with small (<3 mm) lesions or in cases where images are degraded by artefact.