title: Improving bladder cancer imaging using 3-T functional dynamic contrast-enhanced magnetic resonance imaging.
abstract: OBJECTIVE
  The objective of this study was to assess the capability of T2-weighted magnetic resonance imaging (T2W-MRI) and the additional diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) using multitransmit 3 T in the localization of bladder cancer.
  
  
  METHODS
  This prospective study was approved by the local institutional review board. Thirty-six patients were included in the study and provided informed consent. Magnetic resonance imaging scans were performed with T2W-MRI and DCE-MRI on a 3-T multitransmit system. Two observers (with 12 and 25 years of experience) independently interpreted T2W-MRI before DCE-MRI data (maps of pharmacokinetic parameters) to localize bladder tumors. The pathological examination of cystectomy bladder specimens was used as a reference criteria standard. The McNemar test was performed to evaluate the differences in sensitivity, specificity, and accuracy. Scores of κ were calculated to assess interobserver agreement.
  
  
  RESULTS
  The sensitivity, specificity, and accuracy of the localization with T2W-MRI alone were 81% (29/36), 63% (5/8), and 77% (34/44) for observer 1 and 72% (26/36), 63% (5/8), and 70% (31/44) for observer 2. With additional DCE-MRI available, these values were 92% (33/36), 75% (6/8), and 89% (39/44) for observer 1 and 92% (33/36), 63% (5/8), and 86% (38/44) for observer 2. Dynamic contrast-enhanced MRI significantly (P<0.01) improved the sensitivity and accuracy for observer 2. For the 23 patients treated with chemotherapy, DCE-MRI also significantly (P<0.02) improved the sensitivity and accuracy of bladder cancer localization with T2W-MRI alone for observer 2. Scores of κ were 0.63 for T2W-MRI alone and 0.78 for additional DCE-MRI. Of 7 subcentimeter malignant tumors, 4 (57%) were identified on T2W images and 6 (86%) were identified on DCE maps. Of 11 malignant tumors within the bladder wall thickening, 6 (55%) were found on T2W images and 10 (91%) were found on DCE maps.
  
  
  CONCLUSIONS
  Compared with conventional T2W-MRI alone, the addition of DCE-MRI improved interobserver agreement as well as the localization of small malignant tumors and those within bladder wall thickening.
authors.affiliation: From the *Wright Center of Innovation in Biomedical Imaging, Departments of Radiology, †Urology, ‡Internal Medicine, §Pathology, and ∥Center for Biostatistics, The Ohio State University, Columbus, OH.
authors.forename: Huyen T
authors.initials: HT
authors.lastname: Nguyen
authors.forename: Kamal S
authors.initials: KS
authors.lastname: Pohar
authors.forename: Guang
authors.initials: G
authors.lastname: Jia
authors.forename: Zarine K
authors.initials: ZK
authors.lastname: Shah
authors.forename: Amir
authors.initials: A
authors.lastname: Mortazavi
authors.forename: Debra L
authors.initials: DL
authors.lastname: Zynger
authors.forename: Lai
authors.initials: L
authors.lastname: Wei
authors.forename: Daniel
authors.initials: D
authors.lastname: Clark
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Yang
authors.forename: Michael V
authors.initials: MV
authors.lastname: Knopp
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA