title: Functional multiparametric magnetic resonance imaging of the kidneys using blood oxygen level dependent and diffusion-weighted sequences.
abstract: OBJECTIVE
  Little data are available on noninvasive magnetic resonance imaging based assessment of renal function during upper urinary tract obstruction. We determined whether functional multiparametric kidney magnetic resonance imaging could monitor the treatment response in cases of acute unilateral upper urinary tract obstruction.
  
  
  METHODS
  Between January 2008 and January 2010, 18 patients with acute unilateral upper urinary tract obstruction due to calculi were prospectively enrolled to undergo kidney magnetic resonance imaging with conventional, blood oxygen level dependent and diffusion-weighted sequences upon emergency hospital admission and after release of obstruction. We assessed functional imaging parameters of obstructed and contralateral unobstructed kidneys derived from blood oxygen level dependent (apparent spin relaxation rate) and diffusion-weighted (total apparent diffusion coefficient, pure diffusion coefficient and perfusion fraction) sequences during acute upper urinary tract obstruction and after its release.
  
  
  RESULTS
  During acute obstruction the apparent spin relaxation rate and perfusion fraction were lower in the cortex (p=0.020 and 0.031) and medulla (p=0.012 and 0.190, respectively) of obstructed kidneys compared to contralateral unobstructed kidneys. After obstruction release the apparent spin relaxation rate and perfusion fraction increased in the cortex (p=0.016 and 0.004) and medulla (p=0.071 and 0.044, respectively) of formerly obstructed kidneys to values similar to those in contralateral kidneys. Total apparent diffusion coefficient and pure diffusion coefficient values did not significantly differ between obstructed and contralateral unobstructed kidneys during or after obstruction.
  
  
  CONCLUSIONS
  In our patients with acute unilateral upper urinary tract obstruction due to calculi functional kidney magnetic resonance imaging using blood oxygen level dependent and diffusion-weighted sequences enabled us to monitor pathophysiological changes in obstructed kidneys during obstruction and after its release.
authors.affiliation: Department of Urology, University of Bern, Inselspital, Bern, Switzerland.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Giannarini
authors.affiliation: Neuro-Urology, Spinal Cord Injury Centre and Research, University of Zurich, Balgrist University Hospital, Zurich, Switzerland.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Kessler
authors.affiliation: Department of Urology, University of Bern, Inselspital, Bern, Switzerland.
authors.forename: Beat
authors.initials: B
authors.lastname: Roth
authors.affiliation: Department of Radiology, Neuroradiology and Nuclear Medicine, Institute of Diagnostic, Interventional and Pediatric Radiology, University of Bern, Inselspital, Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Vermathen
authors.affiliation: Department of Radiology, Neuroradiology and Nuclear Medicine, Institute of Diagnostic, Interventional and Pediatric Radiology, University of Bern, Inselspital, Bern, Switzerland. Electronic address: harriet.thoeny@insel.ch.
authors.forename: Harriet C
authors.initials: HC
authors.lastname: Thoeny
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011446:Prospective Studies; D014517:Ureteral Obstruction / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D014545:Urinary Calculi / Q000150:complications / Q000503:physiopathology
chemical_list: D010100:Oxygen
keywords: diffusion magnetic resonance imaging; kidney; magnetic resonance imaging; ureteral obstruction; urinary calculi