title: Evolution of MR contrast enhancement patterns during the first week after acute ischemic stroke.
abstract: OBJECTIVE
  Intravascular and parenchymal enhancement have been detected with contrast-enhanced T1-weighted MR imaging in patients with ischemic stroke. Diffusion-weighted MR imaging depicts infarct within minutes after the onset of symptoms. The aims of this study were to study the different MR enhancement findings during the first week after stroke and to ascertain whether the presence of intravascular enhancement over a larger area than the infarct on diffusion-weighted images on day 1 is able to predict substantial infarct growth during the first week.
  
  
  METHODS
  Forty-eight patients were imaged on the first and second days and again 1 week after the onset of ischemic stroke. T1-weighted spin-echo imaging was performed before and after a 0.2 mmol/kg bolus of gadolinium chelate. Diffusion-weighted imaging was performed at the same slice positions. Enhancement findings were categorized as intravascular and parenchymal, with further categorization of parenchymal enhancement as cortical, subcortical, and deep; these findings were then compared with diffusion-weighted imaging findings.
  
  
  RESULTS
  Intravascular enhancement in the infarcted area was detected on day 1 in 78% of the cases, on day 2 in 78% of the cases, and at 1 week in 30% of the cases. Parenchymal enhancement was detected in 26%, 56%, and 100% of the cases, respectively. Intravascular enhancement over a larger area than the infarct on diffusion-weighted images on day 1 was not associated with the extent of infarct growth.
  
  
  CONCLUSIONS
  Detection of different patterns of contrast enhancement can help in determining the age of infarct. Parenchymal enhancement may be intense and can cause diagnostic uncertainty in cases in which the clinical history is obscure.
authors.affiliation: Department of Clinical Radiology, Kuopio University Hospital, Finland.
authors.forename: J O
authors.initials: JO
authors.lastname: Karonen
authors.forename: P L
authors.initials: PL
authors.lastname: Partanen
authors.forename: R L
authors.initials: RL
authors.lastname: Vanninen
authors.forename: P A
authors.initials: PA
authors.lastname: Vainio
authors.forename: H J
authors.initials: HJ
authors.lastname: Aronen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002544:Cerebral Infarction / Q000175:diagnosis; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007511:Ischemia / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000175:diagnosis*; D013997:Time Factors