title: Diffusion-weighted imaging characteristics of biopsy-proven demyelinating brain lesions.
abstract: OBJECTIVE
  To describe lesional diffusion-weighted imaging characteristics in a cohort of patients with biopsy-proven CNS inflammatory demyelinating disease (IDD) and compare diffusion characteristics of ring-enhancing CNS IDD lesions vs abscesses and tumors.
  
  
  METHODS
  Forty prebiopsy apparent diffusion coefficient (ADC) maps were reviewed from 30 patients with CNS IDD. Lesions were analyzed for size, T2-weighted (T2W) hypointense rim, enhancement, and ADC pattern. ADC patterns of CNS IDD ring-enhancing lesions were compared with a published cohort of 35 patients with ring-enhancing tumors and abscesses.
  
  
  RESULTS
  IDD lesions displayed a spectrum of peripheral ADC patterns at the lesion edge: restricted diffusion (low ADC), 33%; increased diffusion (high ADC), 60%; and normal diffusion (homogeneously isointense), 7%. Of biopsied lesions, 93% enhanced (ring, 52%; heterogeneous, 34%; homogeneous, 7%). A hypointense T2W rim was observed in 53%. A ring pattern on ADC (isointense or dark) was associated with T2W hypointense rims (p = 0.02) but not with ring enhancement. On serial imaging, 4 of 7 (57%) patients demonstrated changes in ADC patterns. Peripheral restriction was more common in IDD (p = 0.006) than in tumors or abscesses, whereas central restriction was only observed in abscesses. Restricted lesions in the same stage were more common in the non-IDD cohort (42% vs 20%), with a uniform restricted pattern seen only in abscesses.
  
  
  CONCLUSIONS
  In ring-enhancing lesions, peripheral diffusion restriction is more common in IDD than in tumors/abscesses, whereas central restriction is more common among abscesses. Rapid ADC pattern changes in IDD probably reflect dynamic lesion evolution and may distinguish IDD from tumors.
authors.affiliation: Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: N
authors.initials: N
authors.lastname: Abou Zeid
authors.forename: I
authors.initials: I
authors.lastname: Pirko
authors.forename: B
authors.initials: B
authors.lastname: Erickson
authors.forename: S D
authors.initials: SD
authors.lastname: Weigand
authors.forename: K M
authors.initials: KM
authors.lastname: Thomsen
authors.forename: B
authors.initials: B
authors.lastname: Scheithauer
authors.forename: J E
authors.initials: JE
authors.lastname: Parisi
authors.forename: C
authors.initials: C
authors.lastname: Giannini
authors.forename: L
authors.initials: L
authors.lastname: Linbo
authors.forename: C F
authors.initials: CF
authors.lastname: Lucchinetti
mesh_terms: D000038:Abscess / Q000175:diagnosis / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003711:Demyelinating Diseases / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000145:classification / Q000175:diagnosis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000175:diagnosis / Q000473:pathology; D012189:Retrospective Studies; D016037:Single-Blind Method; D055815:Young Adult