title: Tmax Determined Using a Bayesian Estimation Deconvolution Algorithm Applied to Bolus Tracking Perfusion Imaging: A Digital Phantom Validation Study.
abstract: OBJECTIVE
  The Bayesian estimation algorithm improves the precision of bolus tracking perfusion imaging. However, this algorithm cannot directly calculate Tmax, the time scale widely used to identify ischemic penumbra, because Tmax is a non-physiological, artificial index that reflects the tracer arrival delay (TD) and other parameters. We calculated Tmax from the TD and mean transit time (MTT) obtained by the Bayesian algorithm and determined its accuracy in comparison with Tmax obtained by singular value decomposition (SVD) algorithms.
  
  
  METHODS
  The TD and MTT maps were generated by the Bayesian algorithm applied to digital phantoms with time-concentration curves that reflected a range of values for various perfusion metrics using a global arterial input function. Tmax was calculated from the TD and MTT using constants obtained by a linear least-squares fit to Tmax obtained from the two SVD algorithms that showed the best benchmarks in a previous study. Correlations between the Tmax values obtained by the Bayesian and SVD methods were examined.
  
  
  RESULTS
  The Bayesian algorithm yielded accurate TD and MTT values relative to the true values of the digital phantom. Tmax calculated from the TD and MTT values with the least-squares fit constants showed excellent correlation (Pearson's correlation coefficient = 0.99) and agreement (intraclass correlation coefficient = 0.99) with Tmax obtained from SVD algorithms.
  
  
  CONCLUSIONS
  Quantitative analyses of Tmax values calculated from Bayesian-estimation algorithm-derived TD and MTT from a digital phantom correlated and agreed well with Tmax values determined using SVD algorithms.
authors.affiliation: Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Uwano
authors.forename: Makoto
authors.initials: M
authors.lastname: Sasaki
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kudo
authors.forename: Timothé
authors.initials: T
authors.lastname: Boutelier
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kameda
authors.forename: Futoshi
authors.initials: F
authors.lastname: Mori
authors.forename: Fumio
authors.initials: F
authors.lastname: Yamashita
mesh_terms: D000465:Algorithms; D001499:Bayes Theorem; D006801:Humans; D055420:Perfusion Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*