title: Petrous bone extension of middle-ear acquired cholesteatoma.
abstract: OBJECTIVE
  To describe CT and MR features of extension to the petrous bone, which is a rare complication of acquired cholesteatoma (AC).
  
  
  METHODS
  Postcontrast CT was performed in 4 patients, in axial (n=4) and coronal planes (n=2). The section thickness was 1.2 or 2.5 mm. MR was performed in 3 cases, using T1- and T2-weighted images (n=3) and postcontrast T1-weighted images (n=2).
  
  
  RESULTS
  CT demonstrated a well-outlined lesion involving the petrous bone (n=4). Density could be assessed in 3 cases, showing a hypodense unenhanced mass. Lateral (n=1), superior (n=2), and posterior (n=2) semicircular canals were affected in 3 patients. AC extended to the vestibula, cochlea, and internal acoustic meatus (IAM) in 3 patients. Two ACs extended to the level of IAM, whereas 2 extended further, to the petrous apex. In one case the sphenoid sinus was affected. On MR imaging the lesion was hypointense relative to brain on T1-weighted images and hyperintense on T2-weighted images. MR imaging helped to delineate the lesion and to distinguish it from other cystic lesions of the petrous bone.
  
  
  CONCLUSIONS
  CT and MR offer accurate preoperative assessment of the extension of cholesteatoma, which helps to choose the surgical approach.
authors.affiliation: Service de Radiologie Ouest, Hôpital Claude Huriez CHU, Lille, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Robert
authors.forename: F
authors.initials: F
authors.lastname: Dubrulle
authors.forename: S
authors.initials: S
authors.lastname: Carcasset
authors.forename: C
authors.initials: C
authors.lastname: Hennequin
authors.forename: L
authors.initials: L
authors.lastname: Gaillandre
authors.forename: F M
authors.initials: FM
authors.lastname: Vanecloo
authors.forename: L
authors.initials: L
authors.lastname: Lemaitre
mesh_terms: D000328:Adult; D000368:Aged; D018424:Cholesteatoma, Middle Ear / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010579:Petrous Bone / Q000473:pathology*; D014057:Tomography, X-Ray Computed