title: Modified triexponential analysis of intravoxel incoherent motion for brain perfusion and diffusion.
abstract: BACKGROUND
  To noninvasively obtain more detailed information on brain perfusion and diffusion using modified triexponential analysis.
  
  
  METHODS
  On a 3.0 Tesla MRI, diffusion-weighted imaging of the brain with multiple b-values was performed in healthy volunteers (n = 12). We derived perfusion-related, fast-free, and slow-restricted diffusion coefficients (Dp , Df , and Ds , respectively) and fractions (Fp , Ff , and Fs , respectively) in the frontal and occipital white matter, caudate nucleus, and putamen calculated from triexponential function by a two-step approach. Ds was initially determined using monoexponential function in b-values over 1000 s/mm(2) and was applied to triexponential function. Additionally, the literature value of the diffusion coefficient of free water at 37 °C was assigned to Df . Finally, Dp and fractions were derived using all b-values. Moreover, biexponential analysis was performed and compared with triexponential analysis. We also determined regional cerebral blood flow (rCBF) using arterial spin labeling and assessed its relation with each diffusion parameter.
  
  
  RESULTS
  Significant positive correlations between Dp and rCBF were found in the caudate nucleus (R = 0.84; P = 0.01) and putamen (R = 0.86; P = 0.01), whereas no diffusion parameters were significantly correlated with rCBF on biexponential analysis (P > 0.05 for all).
  
  
  CONCLUSIONS
  Diffusion analysis with triexponential function enables noninvasive gathering of more detailed information on brain perfusion and diffusion.
authors.affiliation: Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ohno
authors.affiliation: Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
authors.forename: Tosiaki
authors.initials: T
authors.lastname: Miyati
authors.affiliation: Department of Radiology, Kanazawa University Hospital, Kanazawa, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Department of Radiology, Kanazawa University Hospital, Kanazawa, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Gabata
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging*; D001931:Brain Mapping / Q000379:methods*; D002421:Caudate Nucleus / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D009038:Motion; D010477:Perfusion; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D055815:Young Adult
keywords: brain; cerebral blood flow; diffusion-weighted imaging; intravoxel incoherent motion; perfusion