title: Differentiation of pyogenic and fungal brain abscesses with susceptibility-weighted MR sequences.
abstract: BACKGROUND
  Conventional magnetic resonance imaging (MRI) techniques are insufficient to determine the causative agent of brain abscesses. We investigated: (1) the value of susceptibility-weighted MR sequences (SWMRS) in the differentiation of fungal and pyogenic brain abscesses; and (2) the effect of different SWMRS (susceptibility-weighted imaging (SWI) versus venous blood oxygen level dependent (VenoBOLD)) for the detection of specific imaging characteristics of pyogenic brain abscesses.
  
  
  METHODS
  We studied six patients with fungal and ten patients with pyogenic brain abscesses. Imaging characteristics on conventional MRI, diffusion-weighted imaging (DWI) and SWMRS were recorded in all abscesses. All lesions were assessed for the presence of a "dual-rim sign" on SWMRS.
  
  
  RESULTS
  Homogenously hyperintense lesions on DWI were present in 60 % of patients with pyogenic abscesses, whereas none of the patients with fungal abscesses showed such lesions. On SWMRS, 90 % of patients with pyogenic abscesses and 60 % of patients with fungal abscesses had only lesions with a low-signal-intensity rim. On SWI, the dual-rim sign was apparent in all pyogenic abscesses. None of the fungal abscesses on SWI (P = 0.005) or any of the pyogenic abscesses on VenoBOLD (P = 0.005) were positive for a dual-rim sign.
  
  
  CONCLUSIONS
  In fungal abscesses, the dual-rim sign is not present but a prominent peripheral rim or central susceptibility effects on SWI will be seen. The appearance of pyogenic abscesses on SWMRS depends on the used sequence, with the dual-rim sign a specific feature of pyogenic brain abscesses on SWI.
authors.affiliation: Department of Radiology, Clinical Hospital Centre Rijeka, Rijeka, Croatia.
authors.forename: Ronald
authors.initials: R
authors.lastname: Antulov
authors.forename: Kresimir
authors.initials: K
authors.lastname: Dolic
authors.forename: Julia
authors.initials: J
authors.lastname: Fruehwald-Pallamar
authors.forename: Damir
authors.initials: D
authors.lastname: Miletic
authors.forename: Majda M
authors.initials: MM
authors.lastname: Thurnher
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001230:Aspergillus; D001421:Bacteria, Anaerobic; D001922:Brain Abscess / Q000175:diagnosis* / Q000382:microbiology*; D002175:Candida; D020314:Central Nervous System Fungal Infections / Q000175:diagnosis* / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D055815:Young Adult
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