Conventional MRI with diffusion-weighted imaging is recommended in patients with a suspicion of cholesteatoma recurrence or residual tumor tissue who have undergone middle ear surgery. On DWI, on images with b-value =1000 s/mm2, a cholesteatoma becomes apparent as a hyperintense focus. On the ADC-map these foci should show a low signal, confirming the presence of diffusion-restriction in these areas. Differential diagnosis can be made with cholesterol granuloma or inflammation, that show high signal on the ADC map. With these findings recurrent cholesteatoma can be detected with 100% specificity. Cholesteatomas up to a size of 2 mm can be detected with this technique. CT scan should be added in case a cholesteatoma is detected for preoperative planning and to exclude perforation of the bony tegmen.
Further differential diagnosis is to be made with cerumen, which shows similar image characteristics to cholesteatoma but is located in the external ear canal. Abscess formation in the middle ear can also show similar imaging findings but has a completely different clinical appearance.