title: Prostatic ductal adenocarcinoma: an aggressive tumour variant unrecognized on T2 weighted magnetic resonance imaging (MRI).
abstract: BACKGROUND
  Prostatic ductal adenocarcinoma (DCa) is an aggressive variant. The purpose of this study was to determine if T2 signal intensity (SI) differs from conventional adenocarcinoma (CCa).
  
  
  METHODS
  A retrospective study of patients who underwent preoperative MRI and prostatectomy between 2009 and 2012 was performed. T2 SI ratios (SIR) for tumour (T) to obturator internus muscle (M) and normal peripheral zone (PZ) were compared. Two radiologists evaluated the central gland/PZ to detect tumours and compared diagnostic accuracy.
  
  
  RESULTS
  T2 SIR for DCa were 3.60 (T/M), 0.66 (T/PZ); 2.68 (T/M), 0.47 (T/PZ) for Gleason 9; 2.50 (T/M), 0.47 (T/PZ) for Gleason 7/8 and 3.95 (T/M), 0.73 (T/PZ) for Gleason 6 tumours. There was a difference in T2 T/M and T/PZ SIR between DCa and Gleason 9 (p = 0.003, p = 0.004) and Gleason 7/8 (p = 0.006, p = 0.002), but no difference in SIR between DCa and Gleason 6 tumours. The sensitivity for tumour detection was 0-27 % for DCa, 64-82 % for Gleason 9, 44-88 % for Gleason 7-8 and 0-20 % for Gleason 6. There was a difference in the sensitivity of detecting Gleason 9 and 7/8 tumours when compared to DCa (p = 0.004, p = 0.001).
  
  
  CONCLUSIONS
  DCa resembles Gleason score 6 tumour at T2-weighted MRI, which underestimates tumour grade and renders the tumour occult.
  
  
  CONCLUSIONS
  Prostatic ductal adenocarcinoma is aggressive, resembling endometrial carcinoma at histopathology. Prostatic ductal adenocarcinoma resembles Gleason score 6 tumour at T2-weighted MRI. MRI grading may underestimate ductal adenocarcinoma based on increased T2 signal.
authors.affiliation: Department of Medical Imaging, The Ottawa Hospital, The University of Ottawa, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9, nschieda@toh.on.ca.
authors.forename: Nicola
authors.initials: N
authors.lastname: Schieda
authors.forename: Niamh
authors.initials: N
authors.lastname: Coffey
authors.forename: Previn
authors.initials: P
authors.lastname: Gulavita
authors.forename: Omran
authors.initials: O
authors.lastname: Al-Dandan
authors.forename: Wael
authors.initials: W
authors.lastname: Shabana
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Flood
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery; D000368:Aged; D044584:Carcinoma, Ductal / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011300:Preoperative Care / Q000379:methods; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000601:surgery; D015203:Reproducibility of Results; D012189:Retrospective Studies