title: Relationships between cerebral perfusion and reversibility of acute diffusion lesions in DEFUSE: insights from RADAR.
abstract: OBJECTIVE
  Acute ischemic lesions with restricted diffusion can resolve after early recanalization. The impact of superimposed perfusion abnormalities on the fate of acute diffusion lesions is unclear.
  
  
  METHODS
  Data were obtained from DEFUSE, a prospective multicenter study of patients treated with IV tPA 3 to 6 hours after stroke onset. Thirty-two patients with baseline diffusion and perfusion lesions and 30 day FLAIR scans were coregistered. The acute diffusion lesion was divided into 3 regions according to the Tmax delay of the superimposed perfusion lesion: normal baseline perfusion; mild-moderately hypoperfused (2 s<Tmax<or=8 s) and severely hypoperfused (Tmax >8 s). The reversal rate was calculated as the percentage of the acute diffusion lesion that did not overlap with the final infarct on 30-day FLAIR. Diffusion reversal rates were compared based on whether a favorable clinical response occurred and whether early recanalization was achieved.
  
  
  RESULTS
  On average, 54% of the acute diffusion lesion volume had normal perfusion. Diffusion reversal rates were significantly increased among cases with favorable clinical response and in patients with early recanalization, especially in regions with normal baseline perfusion. The portion of the diffusion lesion with normal perfusion had significantly higher mean apparent diffusion coefficient values and reversal rates.
  
  
  CONCLUSIONS
  Acute ischemic lesions with restricted diffusion are most likely to recover if reperfusion occurs within 6 hours of symptom onset, and reversibility is associated with early recanalization and favorable clinical outcome. We propose the term RADAR (Reversible Acute Diffusion lesion Already Reperfused) to describe regions of acute restricted diffusion with normal perfusion.
authors.affiliation: Department of Neurology, Stanford Stroke Center, Stanford University Medical center, Palo Alto, CA 94304, USA. jmolivot@stanford.edu
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Olivot
authors.forename: Michael
authors.initials: M
authors.lastname: Mlynash
authors.forename: Vincent N
authors.initials: VN
authors.lastname: Thijs
authors.forename: Archana
authors.initials: A
authors.lastname: Purushotham
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kemp
authors.forename: Maarten G
authors.initials: MG
authors.lastname: Lansberg
authors.forename: Lawrence
authors.initials: L
authors.lastname: Wechsler
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.forename: Michael P
authors.initials: MP
authors.lastname: Marks
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Albers
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D011446:Prospective Studies; D012307:Risk Factors; D020521:Stroke / Q000473:pathology*; D016896:Treatment Outcome