title: Reexamining the quantification of perfusion MRI data in the presence of bolus dispersion.
abstract: OBJECTIVE
  To determine the true impact of dispersion upon cerebral blood flow (CBF) quantification by removing an algorithm implementation-induced systematic error.
  
  
  METHODS
  The impact of dispersion on the arterial input function (AIF) between measurement and entry into the tissue of interest on CBF estimates was simulated assuming: 1) contralateral circulation flow that introduces a true arterial tissue delay (ATD)-related dispersive component; and 2) the presence of an arterial stenosis that disperses and shifts the AIF peak entering the tissue; increasing the apparent ATD relative to the original AIF.
  
  
  RESULTS
  Previously reported CBF estimates for the stenosis dispersion model were found to be a mixture of true dispersive effects and an algorithm implementation-induced systematic error. The true CBF(MEASURED)/CBF(NO-DISPERSION) ratios for short mean transit times (MTT) (normal) and long MTT (infarcted) tissue were similar for both dispersion models evaluated; this was an unanticipated result. The CBF quantification inaccuracies induced through the dispersion model truly related to ATD were lower than for the local stenosis-based dispersion for small ATD values.
  
  
  CONCLUSIONS
  Correcting the systematic error present in a previous deconvolution study removes the reported ATD-related impact on CBF quantification. The impact of dispersion was smaller than half that reported in previous simulation studies.
authors.affiliation: Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Linda
authors.initials: L
authors.lastname: Ko
authors.forename: Marina
authors.initials: M
authors.lastname: Salluzzi
authors.forename: Richard
authors.initials: R
authors.lastname: Frayne
authors.forename: Michael
authors.initials: M
authors.lastname: Smith
mesh_terms: D000465:Algorithms; D001157:Arterial Occlusive Diseases / Q000175:diagnosis; D002539:Cerebral Arterial Diseases / Q000175:diagnosis; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008954:Models, Biological; D013997:Time Factors
chemical_list: D003287:Contrast Media