title: MR imaging features of acute mastoiditis and their clinical relevance.
abstract: OBJECTIVE
  MR imaging is often used for detecting intracranial complications of acute mastoiditis, whereas the intratemporal appearance of mastoiditis has been overlooked. The aim of this study was to assess the imaging features caused by acute mastoiditis in MR imaging and their clinical relevance.
  
  
  METHODS
  Medical records and MR imaging findings of 31 patients with acute mastoiditis (21 adults, 10 children) were analyzed retrospectively. The degree of opacification in the temporal bone, signal and enhancement characteristics, bone destruction, and the presence of complications were correlated with clinical history and outcome data, with pediatric and adult patients compared.
  
  
  RESULTS
  Most patients had ≥50% of the tympanic cavity and 100% of the mastoid antrum and air cells opacified. Compared with CSF, they also showed intramastoid signal changes in T1 spin-echo, T2 TSE, CISS, and DWI sequences; and intramastoid, outer periosteal, and perimastoid dural enhancement. The most common complications in MR imaging were intratemporal abscess (23%), subperiosteal abscess (19%), and labyrinth involvement (16%). Children had a significantly higher prevalence of total opacification of the tympanic cavity (80% versus 19%) and mastoid air cells (90% versus 21%), intense intramastoid enhancement (90% versus 33%), outer cortical bone destruction (70% versus 10%), subperiosteal abscess (50% versus 5%), and perimastoid meningeal enhancement (80% versus 33%).
  
  
  CONCLUSIONS
  Acute mastoiditis causes several intra- and extratemporal changes on MR imaging. Total opacification of the tympanic cavity and the mastoid, intense intramastoid enhancement, perimastoid dural enhancement, bone erosion, and extracranial complications are more frequent in children.
authors.affiliation: From the Department of Radiology, HUS Medical Imaging Center (R.S., G.M., A.T.M.) Department of Radiology (R.S.), East Tallinn Central Hospital, Tallinn, Estonia. riste.saat@hus.fi.
authors.forename: R
authors.initials: R
authors.lastname: Saat
authors.affiliation: Department of Otorhinolaryngology and Head and Neck Surgery (A.H.L.-H., L.J.L., A.A.A., J.P.J.), Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
authors.forename: A H
authors.initials: AH
authors.lastname: Laulajainen-Hongisto
authors.affiliation: From the Department of Radiology, HUS Medical Imaging Center (R.S., G.M., A.T.M.).
authors.forename: G
authors.initials: G
authors.lastname: Mahmood
authors.affiliation: Department of Otorhinolaryngology and Head and Neck Surgery (A.H.L.-H., L.J.L., A.A.A., J.P.J.), Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
authors.forename: L J
authors.initials: LJ
authors.lastname: Lempinen
authors.affiliation: Department of Otorhinolaryngology and Head and Neck Surgery (A.H.L.-H., L.J.L., A.A.A., J.P.J.), Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
authors.forename: A A
authors.initials: AA
authors.lastname: Aarnisalo
authors.affiliation: From the Department of Radiology, HUS Medical Imaging Center (R.S., G.M., A.T.M.).
authors.forename: A T
authors.initials: AT
authors.lastname: Markkola
authors.affiliation: Department of Otorhinolaryngology and Head and Neck Surgery (A.H.L.-H., L.J.L., A.A.A., J.P.J.), Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
authors.forename: J P
authors.initials: JP
authors.lastname: Jero
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging; D004432:Ear, Middle / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008417:Mastoiditis / Q000150:complications* / Q000473:pathology*; D008875:Middle Aged; D012189:Retrospective Studies; D013701:Temporal Bone / Q000473:pathology; D055815:Young Adult