title: Prostate Cancer Detection Using Computed Very High b-value Diffusion-weighted Imaging: How High Should We Go?
abstract: The aim of this study was to assess prostate cancer detection using a broad range of computed b-values up to 5000 s/mm(2).
  
  
  
  This retrospective Health Insurance Portability and Accountability Act-compliant study was approved by an institutional review board with consent waiver. Forty-nine patients (63 ± 8 years) underwent 3T prostate magnetic resonance imaging before prostatectomy. Examinations included diffusion-weighted imaging (DWI) with b-values of 50 and 1000 s/mm(2). Seven computed DWI image sets (b-values: 1000, 1500, 2000, 2500, 3000, 4000, and 5000 s/mm(2)) were generated by mono-exponential fit. Two blinded radiologists (R1 [attending], R2 [fellow]) independently evaluated diffusion weighted image sets for image quality and dominant lesion location. A separate unblinded radiologist placed regions of interest to measure tumor-to-peripheral zone (PZ) contrast. Pathologic findings from prostatectomy served as reference standard. Measures were compared between b-values using the Jonckheere-Terpstra trend test, Spearman correlation coefficient, and generalized estimating equations based on logistic regression for correlated data.
  
  
  
  As b-value increased, tumor-to-PZ contrast and benign prostate suppression for both readers increased (r = +0.65 to +0.71, P ≤ 0.001), whereas anatomic clarity, visualization of the capsule, and visualization of peripheral-transition zone edge decreased (r = -0.69 to -0.75, P ≤ 0.003). Sensitivity for tumor was highest for R1 at b1500-3000 (84%-88%) and for R2 at b1500-2500 (70%-76%). Sensitivities for both pathologic outcomes were lower for both readers at both b1000 and the highest computed b-values. Sensitivity for Gleason >6 tumor was highest for R1 at b1500-3000 (90%-93%) and for R2 at 1500-2500 (78%-80%). The positive predictive value for tumor for R1 was similar from b1000 to 4000 (93%-98%) and for R2 was similar from b1500 to 4000 (88%-94%).
  
  
  
  Computed b-values in the range of 1500-2500 s/mm(2) (but not higher) were optimal for prostate cancer detection; b-values of 1000 or 3000-5000 exhibited overall lower performance.
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016. Electronic address: Andrew.Rosenkrantz@nyumc.org.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016.
authors.forename: Nainesh
authors.initials: N
authors.lastname: Parikh
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016.
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Kierans
authors.affiliation: Department of Pathology, NYU School of Medicine, NYU Langone Medical Center, New York, New York.
authors.forename: Max Xiangtian
authors.initials: MX
authors.lastname: Kong
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016.
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.affiliation: Department of Urology, Division of Urologic Oncology, NYU School of Medicine, NYU Langone Medical Center, New York, New York.
authors.forename: Samir S
authors.initials: SS
authors.lastname: Taneja
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Ream
mesh_terms: D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement; D008297:Male; D008875:Middle Aged; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
keywords: Prostate; diffusion magnetic resonance imaging; imaging; magnetic resonance imaging; neoplasms