Development of granulation tissue in the middle ear cavity is a generalised response to injury/inflammation, chronic otomastoiditis. It can either be typical or go down the pathway of becoming a cholesterol granuloma.
Typical granulation tissue is common, more so than cholesterol granuloma, and has appearances in keeping with granulation tissue anywhere:
Appears as soft tissue attenuation with mild enhancement on contrast administration.
Appears isointense on T1WI and bright contrast enhancement.