Imaging cholesteatoma.

Acquired cholesteatoma of the middle ear is usually diagnosed by otoscopy and treated by exploratory surgery. The role of imaging for such cases is as controversial now as it was 10 years ago, despite significant improvements in spatial and contrast resolution resulting from computerised sectional imaging. We examined 16 cases of straightforward acquired middle ear cholesteatomas with MR as well as high resolution CT scanning to assess the possibilities for tissue characterisation. Cases of the much rarer but more important congenital cholesteatoma of the petrous pyramid with a normal eardrum were also diagnosed by CT and MRI. Magnetic resonance will distinguish cholesteatoma from granulation tissue, fluid and the cholesterol granuloma in the middle ear but this differentiation is of no practical value. An expansile lesion in the petrous apex is most likely to be a cholesteatoma or cholesterol granuloma and is well shown but not differentiated by CT. The two types have quite different characteristics on MR protocols and this is important for planning surgical procedures.