title: Significance of ADC value for detection and characterization of urothelial carcinoma of upper urinary tract using diffusion-weighted MRI.
abstract: OBJECTIVE
  To evaluate utility of diffusion-weighted magnetic resonance imaging (DWI) to detect and predict the histological characteristics of upper urinary tract urothelial carcinomas (UTUCs).
  
  
  METHODS
  We retrospectively evaluated 20 suspicious lesions from 19 patients. MRI study included conventional sequences and DWI with apparent diffusion coefficient (ADC) maps calculated between b = 0 and b = 1,000. ADC values were measured within two different regions of interest (ROI): a small identical ROI placed in the most restrictive part of the tumour and a larger ROI covering two-thirds of the mass surface. The mean ADC values of the tumours were compared with that of normal renal parenchyma using an unpaired Student's t test. Association between ADC values and histological features was tested using non-parametric tests.
  
  
  RESULTS
  Overall, 18 tumours were confirmed histologically as UTUCs. DWI failed to detect two cases of UTUCs (one CIS and one small tumour of 5 mm). There was no statistically significant difference in ADC values measured with the small or large ROI (p = 0.134). The mean ADC value of UTUC was significantly lower than that of the normal renal parenchyma (p < 0.001). No statistical association was found between ADC values and pathological features (location, p = 0.35; grade, p = 0.98; muscle-invasive disease, p = 0.76 and locally advanced stage, p = 0.57).
  
  
  CONCLUSIONS
  DWI may be interesting tool for detecting UTUCs regarding the difference of ADC values between the tumours and surrounding healthy tissues. In regard to low frequency of UTUCs, the association of ADC values and histological characteristics need further investigations in a large prospective multi-institutional study.
authors.affiliation: Department of Nephro-urological Radiology, Claude Huriez Hospital, CHRU Lille, Université Lille Nord de France, 1, Rue Michel Polonovski, 59037, Lille, France.
authors.forename: A
authors.initials: A
authors.lastname: Sufana Iancu
authors.forename: P
authors.initials: P
authors.lastname: Colin
authors.forename: P
authors.initials: P
authors.lastname: Puech
authors.forename: A
authors.initials: A
authors.lastname: Villers
authors.forename: A
authors.initials: A
authors.lastname: Ouzzane
authors.forename: J C
authors.initials: JC
authors.lastname: Fantoni
authors.forename: X
authors.initials: X
authors.lastname: Leroy
authors.forename: L
authors.initials: L
authors.lastname: Lemaitre
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002295:Carcinoma, Transitional Cell / Q000175:diagnosis*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis*; D007682:Kidney Pelvis; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014516:Ureteral Neoplasms / Q000175:diagnosis*