title: Dynamic magnetic resonance imaging in acute pyelonephritis.
abstract: OBJECTIVE
  This study was conducted to evaluate the role and clinical impact of dynamic magnetic resonance imaging (MRI) in the diagnosis and follow-up of acute pyelonephritis (APN).
  
  
  METHODS
  We retrospectively reviewed 442 consecutive renal MRI examinations (279 diagnostic and 163 follow-up) performed in 285 patients (mean age 42.17 years), 35 of whom were kidney transplant recipients with a clinical suspicion of APN.
  
  
  RESULTS
  MRI showed signal abnormalities suggestive of APN in 125/244 (51.2%) patients with native kidneys. Except for two examinations performed without paramagnetic contrast material, the inflammatory foci appeared as areas of nonenhancement: single in 39/123 cases, multiple in 84/123, unilateral in 60/84 and bilateral in 24/84. Abscesses were present in 40/123 (32.5%) positive cases. During follow-up, we observed complete normalisation of MRI signs in 86/103 patients; 17/103 (16.5%) cases evolved into fibrosis and scarring. In 15/35 (42.8%) patients with transplanted kidney, MRI was positive for APN.
  
  
  CONCLUSIONS
  Renal MRI is an effective tool for the diagnosis and follow-up of APN both in patients not at risk and those at higher risk, such as those with a transplanted kidney. The high costs of the examination are offset by better treatment planning and early complication detection.
authors.affiliation: Istituto di Radiologia Diagnostica ed Interventistica, Universitá di Torino, ASOU San Giovanni Battista di Torino, Sede Molinette, Via Genova 3, 10126, Torino, Italy.
authors.forename: M C
authors.initials: MC
authors.lastname: Martina
authors.forename: P P
authors.initials: PP
authors.lastname: Campanino
authors.forename: F
authors.initials: F
authors.lastname: Caraffo
authors.forename: C
authors.initials: C
authors.lastname: Marcuccio
authors.forename: F
authors.initials: F
authors.lastname: Gunetti
authors.forename: L
authors.initials: L
authors.lastname: Colla
authors.forename: M C
authors.initials: MC
authors.lastname: Cassinis
authors.forename: G
authors.initials: G
authors.lastname: Gandini
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D016030:Kidney Transplantation; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011704:Pyelonephritis / Q000175:diagnosis* / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D003287:Contrast Media