title: Effect of using local arterial input functions on cerebral blood flow estimation.
abstract: OBJECTIVE
  To investigate a previously developed method for perfusion-weighted MRI (PWI) cerebral blood flow (CBF) estimation that uses local arterial input functions (AIFs) in stroke patients, and determine its ability to correct delay and/or dispersion (D/D) errors.
  
  
  METHODS
  Analysis was performed on dynamic susceptibility contrast data from 36 stroke patients, and CBF maps were calculated with global- and local-AIF techniques using standard SVP based methods. The ratios of these maps were calculated and the mean ratios were calculated for voxels with both normal and abnormal time to peak or width. The locations of the voxels with high locally-defined to globally-defined CBF ratios were also mapped and the average underlying concentration-time curves for these voxels were calculated.
  
  
  RESULTS
  The ratio of CBF estimates based on local AIFs to global AIFs was on average increased for D/D voxels. The voxels in which this ratio was high were commonly concentrated in the ipsilateral hemisphere, and these voxels also displayed underlying concentration-time curves that showed delay or dispersion. Conversely, there were no such findings based on high globally-defined to locally-defined CBF ratios.
  
  
  CONCLUSIONS
  The local-AIF technique results in an increase in the calculated CBF values for tissues with D/D, consistent with a reduction in the errors associated with D/D.
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Cory
authors.initials: C
authors.lastname: Lorenz
authors.forename: Thomas
authors.initials: T
authors.lastname: Benner
authors.forename: Chloe Joan
authors.initials: CJ
authors.lastname: Lopez
authors.forename: Hakan
authors.initials: H
authors.lastname: Ay
authors.forename: Ming Wang
authors.initials: MW
authors.lastname: Zhu
authors.forename: Hannu
authors.initials: H
authors.lastname: Aronen
authors.forename: Jari
authors.initials: J
authors.lastname: Karonen
authors.forename: Yawu
authors.initials: Y
authors.lastname: Liu
authors.forename: Juho
authors.initials: J
authors.lastname: Nuutinen
authors.forename: A Gregory
authors.initials: AG
authors.lastname: Sorensen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries / Q000473:pathology*; D001776:Blood Circulation Time; D001921:Brain / Q000473:pathology; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D020521:Stroke / Q000473:pathology*