title: Relaxation along fictitious field, diffusion-weighted imaging, and T2 mapping of prostate cancer: Prediction of cancer aggressiveness.
abstract: OBJECTIVE
  To evaluate the performance of relaxation along a fictitious field (RAFF) relaxation time (TRAFF ), diffusion-weighted imaging (DWI)-derived parameters, and T2 relaxation time values for prostate cancer (PCa) detection and characterization.
  
  
  METHODS
  Fifty patients underwent 3T MR examination using surface array coils before prostatectomy. DWI was performed using 14 and 12 b values in the ranges of 0-500 s/mm(2) and 0-2000 s/mm(2) , respectively. Repeated MR examination was performed in 16 patients. TRAFF , DWI-derived parameters (monoexponential, kurtosis, biexponential models), and T2 values were measured and averaged over regions of interest placed in PCa and normal tissue. Repeatability of TRAFF and DWI-derived parameters were assessed by coefficient of repeatability and intraclass correlation coefficient ICC(3,1). Areas under the receiver operating characteristic curve (AUCs) for PCa detection and Gleason score classification were estimated. The parameters were correlated with Gleason score groups using Spearman correlation coefficient (ρ).
  
  
  RESULTS
  ICC(3,1) values for TRAFF were in the range of 0.82-0.92. TRAFF values had higher AUC values for Gleason score classification compared with DWI-derived parameters and T2 . The RAFF method demonstrated the highest ρ value (-0.65).
  
  
  CONCLUSIONS
  In a quantitative region of interest-based analysis, RAFF outperformed DWI ("low" and "high" b values) and T2 mapping in the characterization of PCa.
authors.affiliation: Department of Radiology, University of Turku, Turku, Finland.
authors.forename: Ivan
authors.initials: I
authors.lastname: Jambor
authors.affiliation: Department of Radiology, University of Turku, Turku, Finland.
authors.forename: Marko
authors.initials: M
authors.lastname: Pesola
authors.affiliation: Department of Information Technology, University of Turku, Turku, Finland.|Turku PET Centre, University of Turku, Turku, Finland.
authors.forename: Harri
authors.initials: H
authors.lastname: Merisaari
authors.affiliation: Department of Pathology, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Taimen
authors.affiliation: Department of Urology, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Boström
authors.affiliation: Department of Biotechnology and Molecular Medicine, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.|Imaging Centre, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Liimatainen
authors.affiliation: Department of Radiology, University of Turku, Turku, Finland.|Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku, Finland.
authors.forename: Hannu J
authors.initials: HJ
authors.lastname: Aronen
mesh_terms: D000368:Aged; D019540:Area Under Curve; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D057234:Preoperative Period; D011467:Prostate / Q000000981:diagnostic imaging; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D015203:Reproducibility of Results
keywords: Gleason score; diffusion weighted imaging; prostate cancer; rotating frame relaxation