title: The effect of hormonal treatment on conspicuity of prostate cancer: implications for focal boosting radiotherapy.
abstract: OBJECTIVE
  For focal boosting of prostate tumors, three questions are important regarding the use of hormonal therapy. Does prolonged hormonal treatment affect the conspicuity of tumor tissue on diffusion weighted imaging (DWI) and dynamic contrast-enhanced (DCE-MRI) images? Is tumor delineation possible in patients using hormonal treatment? Can we identify specific imaging thresholds for tumor delineation in patients after prolonged androgen deprivation?
  
  
  METHODS
  Ninety-six patients were included. Using multivariate linear regression analyses, we investigated if DWI and DCE-MRI parameter maps are different in patients receiving hormonal treatment for 0-3 or >3 months. Furthermore, logistic regression was performed to obtain specific imaging thresholds for tumor tissue for the two patient groups.
  
  
  RESULTS
  We found a significantly higher diffusion and lower perfusion of tumor tissue in the >3 months hormonal treatment group compared to the 0-3 group. This resulted in lower tumor conspicuity. Nevertheless, in 18/21 of the patients in the >3 months treatment group, a suspicious lesion could be defined based on the MR images. Based on logistic regression, different imaging thresholds should be set for tumor detection in the two treatment groups.
  
  
  CONCLUSIONS
  Prolonged androgen deprivation decreases tumor conspicuity. Different imaging thresholds need to be set to delineate tumor in patients who have had prolonged hormonal treatment.
authors.affiliation: University Medical Center Utrecht, The Netherlands. G.Groenendaal-2@umcutrecht.nl
authors.forename: Greetje
authors.initials: G
authors.lastname: Groenendaal
authors.forename: Marco
authors.initials: M
authors.lastname: van Vulpen
authors.forename: Susanne R
authors.initials: SR
authors.lastname: Pereboom
authors.forename: Davey
authors.initials: D
authors.lastname: Poelma-Tap
authors.forename: Johannes G
authors.initials: JG
authors.lastname: Korporaal
authors.forename: Evelyn
authors.initials: E
authors.lastname: Monninkhof
authors.forename: Uulke A
authors.initials: UA
authors.lastname: van der Heide
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000627:therapeutic use*; D001918:Brachytherapy; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies
chemical_list: D000726:Androgen Antagonists; D007457:Iodine Radioisotopes