title: Utility of quantitative MRI metrics for assessment of stage and grade of urothelial carcinoma of the bladder: preliminary results.
abstract: OBJECTIVE
  The purpose of this study was to assess associations between quantitative MRI metrics and pathologic indicators of aggressiveness of urothelial carcinoma of the bladder.
  
  
  METHODS
  In this retrospective biinstitutional study, 37 patients (28 men and nine women; mean age, 73 ± 12 years) who underwent pelvic MRI including diffusion-weighted imaging (b values 0, 400, and 800 s/mm(2)) and T2-weighted imaging before transurethral resection or cystectomy for urothelial carcinoma of the bladder were identified. Tumor diameter (measured on T2-weighted imaging), normalized T2 signal intensity (to muscle; hereafter labeled normalized T2) and apparent diffusion coefficient (ADC) were measured for all tumors. Mann-Whitney test and receiver operating characteristic analyses were used to identify associations between these metrics and histopathologic tumor stage and grade.
  
  
  RESULTS
  Thirty-seven tumors were assessed (mean size, 35 ± 23 mm; range 8-88 mm). At histopathologic analysis, 16 of 37 (43%) tumors were stage T2 or greater and 21 of 37 (57%) were stage T1 or lower, whereas 34 of 37 (92%) were high grade and three of 37 (8%) were low grade. High-stage (≥ T2) tumors showed greater tumor diameter, lower normalized T2, and lower ADC (p = 0.005-0.032) than low-stage (≤ T1) tumors. Tumor diameter and ADC were significant independent predictors of stage (p ≤ 0.043), with their combination giving an area-under the-curve (AUC) of 0.804. High-grade tumors showed significantly lower ADC (p = 0.023) but no significant difference in tumor diameter or normalized T2 (p = 0.201-0.559). AUC for differentiating low- and high-grade tumors was higher for ADC (0.902) than for tumor diameter (0.603) or normalized T2 (0.725).
  
  
  CONCLUSIONS
  A combination of size and quantitative MRI metrics can potentially be used as markers of stage and grade of bladder cancer.
authors.affiliation: 1 Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 560 First Ave, TCH-HW202, New York, NY 10016.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
authors.forename: Mohammad
authors.initials: M
authors.lastname: Haghighi
authors.forename: Jeremy
authors.initials: J
authors.lastname: Horn
authors.forename: Mohit
authors.initials: M
authors.lastname: Naik
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hardie
authors.forename: Molly B
authors.initials: MB
authors.lastname: Somberg
authors.forename: Jonathan
authors.initials: J
authors.lastname: Melamed
authors.forename: Guang-Qian
authors.initials: GQ
authors.lastname: Xiao
authors.forename: William C
authors.initials: WC
authors.lastname: Huang
authors.forename: Bachir
authors.initials: B
authors.lastname: Taouli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002295:Carcinoma, Transitional Cell / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D001749:Urinary Bladder Neoplasms / Q000473:pathology*