title: Determination of the Association Between T2-weighted MRI and Gleason Sub-pattern: A Proof of Principle Study.
abstract: The study aimed to determine the relationship between T2-weighted magnetic resonance imaging (MRI) signal and histologic sub-patterns in prostate cancer areas with different Gleason grades.
  
  
  
  MR images of prostates (n = 25) were obtained prior to radical prostatectomy. These were processed as whole-mount specimens with tumors and the peripheral zone was annotated digitally by two pathologists. Gleason grade 3 was the most prevalent grade and was subdivided into packed, intermediate, and sparse based on gland-to-stroma ratio. Large cribriform, intraductal carcinoma, and small cribriform glands (grade 4 group) were separately annotated but grouped together for statistical analysis. The log MRI signal intensity for each contoured region (n = 809) was measured, and pairwise comparisons were performed using the open-source software R version 3.0.1.
  
  
  
  Packed grade 3 sub-pattern has a significantly lower MRI intensity than the grade 4 group (P < 0.00001). Sparse grade 3 has a significantly higher MRI intensity than the packed grade 3 sub-pattern (P < 0.0001). No significant difference in MRI intensity was observed between the Gleason grade 4 group and the sparse sub-pattern grade 3 group (P = 0.54). In multivariable analysis adjusting for peripheral zone, the P values maintained significance (packed grade 3 group vs grade 4 group, P < 0.001; and sparse grade 3 sub-pattern vs packed grade 3 sub-pattern, P < 0.001).
  
  
  
  This study demonstrated that T2-weighted MRI signal is dependent on histologic sub-patterns within Gleason grades 3 and 4 cancers, which may have implications for directed biopsy sampling and patient management.
authors.affiliation: Department of Pathology, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada. Electronic address: michelle.downes@sunnybrook.ca.
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Downes
authors.affiliation: Robarts Research Institute, University of Western Ontario, London, Ontario, Canada; Biomedical Engineering Graduate Program, University of Western Ontario, London, Ontario, Canada.
authors.forename: Eli
authors.initials: E
authors.lastname: Gibson
authors.affiliation: Department of Biostatistics, St. Michael's Hospital, Toronto, Ontario, Canada; Princess Margaret Cancer Centre, University Health Network, Toronto, Canada.
authors.forename: Jenna
authors.initials: J
authors.lastname: Sykes
authors.affiliation: Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Masoom
authors.initials: M
authors.lastname: Haider
authors.affiliation: Department of Pathology, University Health Network, Toronto, Ontario, Canada.
authors.forename: Theo H
authors.initials: TH
authors.lastname: van der Kwast
authors.affiliation: Departments of Medical Biophysics and Oncology, Biomedical Engineering Graduate Program, University of Western Ontario, Lawson Health Research Institute, London Regional Cancer Program, London, Ontario, Canada.
authors.forename: Aaron
authors.initials: A
authors.lastname: Ward
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery
keywords: Prostate; T2W; sub-pattern