title: MR imaging in acute stroke: diffusion-weighted and perfusion imaging parameters for predicting infarct size.
abstract: OBJECTIVE
  To investigate the predictive value of the ischemic lesion size, as depicted in the acute stroke phase on diffusion-weighted magnetic resonance (MR) images and time-to-peak (TTP) maps of tissue perfusion imaging, for infarct size, as derived from T2-weighted imaging in the postacute phase.
  
  
  METHODS
  Fifty patients who underwent diffusion-weighted and perfusion imaging within 1-24 hours after stroke onset and a follow-up T2-weighted investigation after about 8 days were included. Lesion volumes were evaluated by using a semiautomatic thresholding technique. Volumetric results of acute diffusion-weighted and perfusion imaging were analyzed in comparison with follow-up T2-weighted images and in terms of the time difference between symptom onset and initial MR imaging.
  
  
  RESULTS
  At diffusion-weighted imaging, the acute lesion defined by a signal intensity increase of more than 20%, compared with the contralateral side, showed the best correlation with the infarct size after 1 week. At perfusion imaging, the best predictor relative to the contralateral side was a delay of more than 6 seconds on TTP maps. Temporal analysis of volumetric results, which depended on the time difference between symptom onset and examination, revealed two patient subgroups.
  
  
  CONCLUSIONS
  Diffusion-weighted imaging helped to predict the size of the lesion on T2-weighted images obtained after about 8 days in patients with a symptom onset of more than 4 hours (r = 0.96), while in patients with a symptom onset of less than 4 hours, perfusion imaging provided important additional information about brain tissue with impaired perfusion.
authors.affiliation: Department of Neurology, Heinrich-Heine University of Düsseldorf, MNR-Klinik/MRT-2, Moorenstrasse 5, D-40225 Düsseldorf, Germany. wittsackuni-duesseldorf.de
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Wittsack
authors.forename: Afra
authors.initials: A
authors.lastname: Ritzl
authors.forename: Gereon R
authors.initials: GR
authors.lastname: Fink
authors.forename: Frank
authors.initials: F
authors.lastname: Wenserski
authors.forename: Mario
authors.initials: M
authors.lastname: Siebler
authors.forename: Rüdiger J
authors.initials: RJ
authors.lastname: Seitz
authors.forename: Ulrich
authors.initials: U
authors.lastname: Mödder
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Freund
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020520:Brain Infarction / Q000473:pathology*; D004058:Diffusion; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010477:Perfusion; D011237:Predictive Value of Tests