Whilst the method of canal wall down and same-session reconstruction is emerging to be more popular, canal wall up procedures are still performed. In either, it is necessary to ensure eradication of cholesteatoma or detect its recurrence. The reliability of non-planar diffusion weighted magnetic resonance imaging is brought into focus in this study of 107 patients. A cholesteatoma protocol for MRI imaging was followed and, in particular, pixel-based signal intensity threshold was calculated as the average between grey-scale pixel value in the relevant regions. Then the average grey-scale pixel value ratio between the lesion and temporal lobe and also between the lesion and the pons was statistically analysed and used as a main diagnostic tool. This indicated a high probability of cholesteatoma. The authors contend this obviates the need for further supportive imaging in equivocal cases. Lesions smaller than 3mm had to be excluded. Forty percent of these patients had previous surgery. The study showed 84% sensitivity and 98% specificity. Three cases had discrepancy between clinical and radiological diagnosis. Of these, only one was found to be false positive at surgery. Balanced reliability on non-planar diffusion weighted MRI can reduce the cost and impact of ‘second look’ surgery and allow ENT departments to meet their other needs.