title: An improved model for describing the contrast bolus in perfusion MRI.
abstract: OBJECTIVE
  Quantification of perfusion measurements using dynamic, susceptibility-weighted contrast-enhanced (DSC) MRI depends on estimating the size and shape of the tracer bolus. Typically, the bolus is described as a gamma variate function (GV) fitted to the bolus portion of tracer concentration time curve (CTC). However, the last point to fit is arbitrary which can lead to considerable variation in the fitted curve in the presence of noise. In this technical note, we present a model which takes into account recirculation explicitly and fits robustly to the entire CTC in the presence of noise.
  
  
  METHODS
  Signal data measurements from ten DSC MRI patients were fitted with our new model and a GV function using four different methods of estimating the end of the bolus. Estimates of the area under the curves (AUC) and first moments (FMs) of the bolus were compared at different noise levels.
  
  
  RESULTS
  The new model gave errors similar to or smaller than those of the most effective methods for fitting a GV.
  
  
  CONCLUSIONS
  The single compartment recirculation (SCR) model is the most robust fitting technique with respect to noise both for bias and variability.
authors.affiliation: Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, 660 First Avenue, New York, New York 10016, USA. Vishal.Patil@nyumc.org
authors.forename: Vishal
authors.initials: V
authors.lastname: Patil
authors.forename: Glyn
authors.initials: G
authors.lastname: Johnson
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA