title: Relationship between apparent diffusion coefficients at 3.0-T MR imaging and Gleason grade in peripheral zone prostate cancer.
abstract: OBJECTIVE
  To retrospectively determine the relationship between apparent diffusion coefficients (ADCs) obtained with 3.0-T diffusion-weighted (DW) magnetic resonance (MR) imaging and Gleason grades in peripheral zone prostate cancer.
  
  
  METHODS
  The requirement to obtain institutional review board approval was waived. Fifty-one patients with prostate cancer underwent MR imaging before prostatectomy, including DW MR imaging with b values of 0, 50, 500, and 800 sec/mm(2). In prostatectomy specimens, separate slice-by-slice determinations of Gleason grade groups were performed according to primary, secondary, and tertiary Gleason grades. In addition, tumors were classified into qualitative grade groups (low-, intermediate-, or high-grade tumors). ADC maps were aligned to step-sections and regions of interest annotated for each tumor slice. The median ADC of tumors was related to qualitative grade groups with linear mixed-model regression analysis. The accuracy of the median ADC in the most aggressive tumor component in the differentiation of low- from combined intermediate- and high-grade tumors was summarized by using the area under the receiver operating characteristic (ROC) curve (A(z)).
  
  
  RESULTS
  In 51 prostatectomy specimens, 62 different tumors and 251 step-section tumor lesions were identified. The median ADC in the tumors showed a negative relationship with Gleason grade group, and differences among the three qualitative grade groups were statistically significant (P < .001). Overall, with an increase of one qualitative grade group, the median ADC (±standard deviation) decreased 0.18 × 10(-3) mm(2)/sec ± 0.02. Low-, intermediate-, and high-grade tumors had a median ADC of 1.30 × 10(-3) mm(2)/sec ± 0.30, 1.07 × 10(-3) mm(2)/sec ± 0.30, and 0.94 × 10(-3) mm(2)/sec ± 0.30, respectively. ROC analysis showed a discriminatory performance of A(z) = 0.90 in discerning low-grade from combined intermediate- and high-grade lesions.
  
  
  CONCLUSIONS
  ADCs at 3.0 T showed an inverse relationship to Gleason grades in peripheral zone prostate cancer. A high discriminatory performance was achieved in the differentiation of low-, intermediate-, and high-grade cancer.
authors.affiliation: Department of Radiology, University Medical Centre St. Radboud, PO Box 9101, 6500HB, Nijmegen, The Netherlands. t.hambrock@rad.umcn.nl
authors.forename: Thomas
authors.initials: T
authors.lastname: Hambrock
authors.forename: Diederik M
authors.initials: DM
authors.lastname: Somford
authors.forename: Henkjan J
authors.initials: HJ
authors.lastname: Huisman
authors.forename: Inge M
authors.initials: IM
authors.lastname: van Oort
authors.forename: J Alfred
authors.initials: JA
authors.lastname: Witjes
authors.forename: Christina A
authors.initials: CA
authors.lastname: Hulsbergen-van de Kaa
authors.forename: Thomas
authors.initials: T
authors.lastname: Scheenen
authors.forename: Jelle O
authors.initials: JO
authors.lastname: Barentsz
mesh_terms: D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000601:surgery; D012372:ROC Curve; D012189:Retrospective Studies