title: Tissue at risk is overestimated in perfusion-weighted imaging: MR imaging in acute stroke patients without vessel recanalization.
abstract: OBJECTIVE
  The volume of decreased cerebral blood flow (CBF) in acute stroke perfusion-weighted imaging frequently overestimates final infarct volume. We hypothesized that surviving tissue exists even in patients without recanalization and tried to determine perfusion thresholds from initial MR imaging.
  
  
  METHODS
  Stroke MR imaging including MR angiography was carried out at days 0, 1, and 7 after stroke onset in 19 patients without recanalization at least until day 1. The following lesions were defined: L0 = diffusion restriction at day 0; LG1 = lesion growth until day 1; LG7 = lesion growth until day 7; ST7 = initially hypoperfused, but surviving tissue. These lesions were transferred on initial MR imaging within 4.7 hours and perfusion values at day 0 were determined.
  
  
  RESULTS
  Median lesion volume L0 at day 0 was 18.2 mL and increased to 39.4 and 43.8 mL at days 1 and 7. Volume of decreased rCBF not progressing to infarction was 148.5 mL (ST7). Mean ST7 perfusion values were different from L0 and LG1, but only mean relative cerebral blood volume (rCBV) was different from LG7, discriminating survival against death of tissue. A threshold value of 0.82 CBV for death versus survival was determined with a sensitivity of 0.56 and specificity of 0.95. Carotid T occlusions showed the greatest potential of lesion growth.
  
  
  CONCLUSIONS
  Even when vessel occlusion persists, hypoperfused tissue on MR imaging does not necessarily progress toward infarction. The most conclusive inferences can be drawn from CBV images. The site of arterial occlusion also determines progression to infarction.
authors.affiliation: Department of Neuroradiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kucinski
authors.forename: Dirk
authors.initials: D
authors.lastname: Naumann
authors.forename: René
authors.initials: R
authors.lastname: Knab
authors.forename: Volker
authors.initials: V
authors.lastname: Schoder
authors.forename: Susanne
authors.initials: S
authors.lastname: Wegener
authors.forename: Jens
authors.initials: J
authors.lastname: Fiehler
authors.forename: Amitava
authors.initials: A
authors.lastname: Majumder
authors.forename: Joachim
authors.initials: J
authors.lastname: Röther
authors.forename: Hermann
authors.initials: H
authors.lastname: Zeumer
mesh_terms: D000328:Adult; D000368:Aged; D002545:Brain Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis* / Q000503:physiopathology