Numerical assessment of cholesteatoma by signal intensity on non-EP-DWI and ADC maps.

Objective: To establish a methodology for magnetic resonance imaging (MRI) assessment in the diagnosis of cholesteatoma using signal intensity on BLADE diffusion-weighted MRI (BLADE-DWI) and apparent diffusion coefficient (ADC) mapping.
Study Design: Retrospective case series.
Setting: University hospital.
Patients: Participants comprised 29 patients who underwent middle ear surgery and in whom preoperative differential diagnosis between cholesteatoma and other middle ear diseases was difficult using local and computed tomographic findings and required BLADE-DWI.
Intervention: Signal intensity ratio (SIR) between the affected region of the middle ear and the pons measured by BLADE-DWI and on ADC maps was evaluated numerically. SIR in an area located near the target lesion in each case was used as a control. Values were compared between both cases in which cholesteatoma was histopathologically confirmed (cholesteatoma group) and cases in which cholesteatoma was excluded on histopathologic examination (noncholesteatoma group).
Main Outcome Measures: Imaging and histopathologic findings.
Results: SIR on BLADE-DWI was significantly higher in the cholesteatoma group than in the noncholesteatoma group, although both groups showed significantly higher SIR in the target lesion than in the control area. Moreover, SIR on ADC maps was significantly lower in the cholesteatoma group than in the noncholesteatoma group. The clear cutoff value of SIR on ADC maps was 1.5.
Conclusion: The combination of BLADE-DWI and ADC mapping offers a useful imaging tool for accurate detection of middle ear cholesteatoma. Use of SIR can numerically differentiate between cholesteatoma and noncholesteatoma.