title: Diffusion-weighted imaging and apparent diffusion coefficient values versus contrast-enhanced MR imaging in the identification and characterisation of acute pyelonephritis.
abstract: OBJECTIVE
  To compare contrast-enhanced (CEMR) and diffusion-weighted (DWI) magnetic resonance imaging in diagnosing acute pyelonephritis (APN) and to assess ADC measurement reliability in differentiating among normal renal parenchyma, APN and abscesses.
  
  
  METHODS
  Eighty-eight patients (80 women, mean age 36.5 years) with clinical suspicion of APN were retrospectively reviewed. An experienced observer quantified lesions with a score ranging from 0 to 3. DWI and CEMR were compared on the basis of the assigned score, total examination number (88) and on presence (36)/absence (52) of abscesses. ADC values, calculated at the healthy parenchyma, APN and abscessed were compared to each other.
  
  
  RESULTS
  Agreement between CEMR and DWI was 94.3 % (83/88 patients; P < 0.05). In the APN group, DWI was awarded the highest visibility score compared to CEMR (P = 0.05), while in the abscess group CEMR had the highest score (P = 0.04). The difference between ADC values of the APN-healthy parenchyma and abscess-APN groups was significant (P < 0.05). The area under the ROC curve of ADC values of the APN-healthy and abscess-APN groups were found to be 0.94 (95 % CI; cutoff value = 2) and 0.78 (95 % CI; cutoff value = 1.2) respectively.
  
  
  CONCLUSIONS
  Diffusion-weighted imaging appears reliable in the diagnosis and follow-up of acute pyelonephritis and could provide a reasonable alternative to contrast-enhanced magnetic resonance imaging.
authors.affiliation: Radiology Institute, Department of Surgical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy, riccardo_faletti@yahoo.it.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Faletti
authors.forename: Maria Carla
authors.initials: MC
authors.lastname: Cassinis
authors.forename: Paolo
authors.initials: P
authors.lastname: Fonio
authors.forename: Angela
authors.initials: A
authors.lastname: Grasso
authors.forename: Giacomo
authors.initials: G
authors.lastname: Battisti
authors.forename: Laura
authors.initials: L
authors.lastname: Bergamasco
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gandini
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011704:Pyelonephritis / Q000175:diagnosis*; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media