title: Contrast-enhanced MR imaging in acute ischemic stroke: T2* measures of blood-brain barrier permeability and their relationship to T1 estimates and hemorrhagic transformation.
abstract: OBJECTIVE
  rtPA is an effective treatment for AIS, yet it is substantially underused due to the increased risk of HT. Recent work suggests that permeability-related information can be extracted from routine T2*-based perfusion images by measuring the rR of the contrast agent. Given that other T2*-based measures have recently been proposed, the purpose of this study was to evaluate 4 such permeability measures in identifying patients with AIS who will proceed to HT.
  
  
  METHODS
  Eighteen patients with AIS were examined within a mean of 3.3 +/- 1.4 hours postonset. Dynamic T2*-weighted imaging consisted of a single-shot EPI following a bolus of gadodiamide. HT was determined on follow-up CT or MR imaging at 24-72 hours. Mean values of rR, Peak Height, Recovery, as well as Slope were calculated and analyzed on the basis of follow-up HT status.
  
  
  RESULTS
  Eight patients proceeded to HT. The mean rR for patients with HT was significantly greater than that for patients without HT (0.22 +/- 0.06 versus 0.14 +/- 0.06, P = .006), while there was a trend toward decreased %Recovery in patients with HT (76 +/- 6 versus 82 +/- 11%, P = .092). There was a significant negative correlation between %Recovery and rR (r = -0.88, P < .001). No significant differences or trends were detected with respect to Peak Height or Slope.
  
  
  CONCLUSIONS
  Both rR and %Recovery can be readily extracted from a routine perfusion MR imaging dataset and show potential for identifying HT during the acute phase poststroke.
authors.affiliation: Department of Medical Imaging, University of Toronto, 150 College Street, Toronto, Ontario, Canada.
authors.forename: R E
authors.initials: RE
authors.lastname: Thornhill
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: W
authors.initials: W
authors.lastname: Rammo
authors.forename: D J
authors.initials: DJ
authors.lastname: Mikulis
authors.forename: A
authors.initials: A
authors.lastname: Kassner
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001812:Blood-Brain Barrier / Q000378:metabolism / Q000473:pathology*; D002545:Brain Ischemia / Q000378:metabolism / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000378:metabolism / Q000473:pathology*; D003287:Contrast Media; D018450:Disease Progression; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011237:Predictive Value of Tests; D020127:Recovery of Function; D012189:Retrospective Studies; D020521:Stroke / Q000378:metabolism / Q000473:pathology*
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA