title: Acute pyelonephritis in transplanted kidneys: can diffusion-weighted magnetic resonance imaging be useful for diagnosis and follow-up?
abstract: OBJECTIVE
  To assess reliability of diffusion-weighted magnetic resonance imaging (DW-MRI) in the management of acute pyelonephritis (APN) foci in transplanted kidneys.
  
  
  METHODS
  In the 2012-2014 period, 24 kidney-transplanted patients underwent MR screening for clinical suspicion of APN. Two readers independently analyzed all images, establishing presence and location of APN foci. The 22 patients who were positive at the MR exam constituted the study population. For each patient the apparent diffusion coefficient (ADC) was measured in the APN foci and in three sites of the healthy parenchyma (case-control comparison). The data were matched to the laboratory measurements for white blood cell, C-reactive protein, and serum creatinine.
  
  
  RESULTS
  Forty-six APN foci were found in 22/24 patients. At the acute stage, the difference in ADC between healthy parenchyma and APN foci was significant (2.06 ± 0.16 vs. 1.43 ± 0.32 × 10(-3) mm(2)/s; p < 0.0001). The performance of ADC as APN indicator was tested by the receiving operating characteristics (ROC) curve: the area under curve AUC = 0.99 witnessed an excellent discriminatory ability, with threshold APN/normal parenchyma 1.9 × 10(-3) mm(2)/s. At the 1-month follow-up 43/46 APN foci were no longer visible, with ADC values significantly higher than at the acute stage; all laboratory data were physiological, with WBC significantly reduced from the acute phase (5.2 ± 1.6 × 10(9)/L vs. 10.6 ± 4.8 × 10(9)/L; p < 0.0001). The other 3 patients underwent further therapy and exams, including a third MR.
  
  
  CONCLUSIONS
  DW-MRI with ADC measurement seems to be a reliable tool in diagnosing and monitoring APN foci in transplanted kidneys, with clinical impact on patient management.
authors.affiliation: Radiology Unit, Department of Surgical Sciences, University of Torino, Via Genova 3, 10126, Turin, Italy. riccardo_faletti@yahoo.it.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Faletti
authors.affiliation: Radiology Unit, Department of Surgical Sciences, University of Torino, Via Genova 3, 10126, Turin, Italy.
authors.forename: Maria Carla
authors.initials: MC
authors.lastname: Cassinis
authors.affiliation: Radiology Unit, Department of Surgical Sciences, University of Torino, Via Genova 3, 10126, Turin, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Gatti
authors.affiliation: Radiology Unit, Department of Surgical Sciences, University of Torino, Via Genova 3, 10126, Turin, Italy.
authors.forename: Jacopo
authors.initials: J
authors.lastname: Giglio
authors.affiliation: Radiology Unit, Department of Surgical Sciences, University of Torino, Via Genova 3, 10126, Turin, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Guarnaccia
authors.affiliation: Renal Transplantation Unit, Division of Nephrology Dialysis and Transplantation, AOU Città della Salute e della Scienza di Torino and Department of Medical Sciences, University of Torino, Turin, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Messina
authors.affiliation: Radiology Unit, Department of Surgical Sciences, University of Torino, Via Genova 3, 10126, Turin, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Bergamasco
authors.affiliation: Radiology Unit, Department of Surgical Sciences, University of Torino, Via Genova 3, 10126, Turin, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Fonio
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging*; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000473:pathology; D011704:Pyelonephritis / Q000000981:diagnostic imaging* / Q000473:pathology; D015203:Reproducibility of Results
keywords: Apparent diffusion coefficient; Diffusion-weighted MRI; Kidney transplantation; Pyelonephritis; Urinary tract infection