title: Triexponential function analysis of diffusion-weighted MRI for diagnosing prostate cancer.
abstract: BACKGROUND
  To evaluate more detailed information noninvasively through on diffusion and perfusion in prostate cancer (PCa) using triexponential analysis of diffusion-weighted imaging (DWI).
  
  
  METHODS
  Sixty-three prostate cancer patients underwent preoperative 3.0 Tesla MRI including eight b-values DWI. Triexponential analysis was performed to obtain three diffusion coefficients (Dp , Df , Ds ), as well as fractions (Fp , Ff , Fs ). Each diffusion parameter for cancerous lesions and normal tissues was compared and the relationship between diffusion parameters and Gleason score (GS) was assessed. K(trans) , Ve , and the ratios of intracellular components measured in histopathological specimens were compared with diffusion parameters.
  
  
  RESULTS
  Dp was significantly greater for cancerous lesions than normal peripheral zone (PZ) (P < 0.001), whereas Dp in transition zone (TZ) showed no significant difference (P = 0.74, 95% confidence interval (CI) = -4.69-6.48). Ds was significantly smaller for each cancerous lesions in PZ and TZ (P < 0.001, respectively). There was no significant difference in Df between cancerous lesions and normal tissues in PZ and TZ (P = 0.07, 95% CI = -0.29-0.12 and P = 0.53, 95% CI = -3.51-2.29, respectively). D obtained with biexponential analysis were significantly smaller in cancerous lesions than in normal tissue in PZ and TZ (P < 0.001 for both), while D* in PZ and TZ showed no significant difference (P = 0.14, 95% CI = -1.60-0.24 and P = 0.31, 95% CI = -3.43-1.16, respectively). Dp in PZ and TZ showed significant correlation with K(trans) (R = 0.85, P < 0.001; R = 0.81, P < 0.001, respectively), while D(*) in PZ obtained with biexponential analysis showed no such correlation (P = 0.08, 95% CI = -0.14-0.30). Fs was significantly correlated with intracellular space fraction evaluated in histopathological specimens in PZ and TZ cancer (R = 0.41, P < 0.05; R = 0.59, P < 0.001, respectively). Ff and Fs correlated significantly with GS in PZ and TZ cancer (PZ: R = -0.44, P < 0.05; R = 0.37, P < 0.05, TZ: R = -0.59, P < 0.05; R = 0.57, P < 0.05, respectively).
  
  
  CONCLUSIONS
  Triexponential analysis is a noninvasive approach that can provide more detailed information regarding diffusion and perfusion of PCa than biexponential analysis.
authors.affiliation: Division of Radiology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ueda
authors.affiliation: Department of Radiology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Takahashi
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: Division of Radiology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Katsusuke
authors.initials: K
authors.lastname: Kyotani
authors.affiliation: Division of Radiology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kawamitu
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: Division of Radiology, University Hospital of the Ryukyus, Nishihara, Okinawa.
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Aoyama
authors.affiliation: Department of Radiology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Ueno
authors.affiliation: Department of Radiology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kitajima
authors.affiliation: Department of Pathology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Fumi
authors.initials: F
authors.lastname: Kawakami
authors.affiliation: Philips Healthcare Asia Pacific.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Okuaki
authors.affiliation: Department of Pathology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Ryuko
authors.initials: R
authors.lastname: Tsukamoto
authors.affiliation: Department of Pathology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Emmy
authors.initials: E
authors.lastname: Yanagita
authors.affiliation: Department of Radiology, Kobe University Hospital, Chuo-ku Kobe, Hyogo, Japan.
authors.forename: Kazuro
authors.initials: K
authors.lastname: Sugimura
mesh_terms: D000368:Aged; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D009716:Numerical Analysis, Computer-Assisted; D011471:Prostatic Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: apparent diffusion coefficient (ADC); diffusion weighted imaging (DWI); intravoxel incoherent motion (IVIM); perfusion; prostate; triexponential analysis