title: Intrarenal oxygenation by blood oxygenation level-dependent MRI in contrast nephropathy model: effect of the viscosity and dose.
abstract: OBJECTIVE
  To compare the effects of osmolality versus viscosity of radio-contrast media on intra-renal oxygenation as determined by blood oxygenation level-dependent (BOLD) MRI in a model of contrast induced nephropathy (CIN).
  
  
  METHODS
  Twenty-four Sprague-Dawley rats were divided into five groups. Nitric oxide synthase inhibitor L-NAME (10 mg/kg), cyclooxygenase inhibitor indomethacin (10 mg/kg), or saline, and radio-contrast iodixanol (high viscosity, 784 or 1600 mg I/kg) or iothalamate (high osmolality, 1600 mg I/kg) were administered. BOLD MRI images were acquired on Siemens 3 Tesla (T) scanner using a multiple gradient recalled echo sequence at baseline, following L-NAME (or saline), indomethacin (or saline), and radio-contrast agents. R2* (=1/T2*) was used as the BOLD MRI parameter in renal medulla and cortex. Mixed-effects models with first order auto-regressive variance-covariance models were used to analyze the data.
  
  
  RESULTS
  The magnitude of change in medullary R2* (MR2*) with same dose of iodine was larger with iodixanol compared with iothalalmate both in pretreated groups (303% versus 225.6%, < 0.01) and the control group (191.6% versus -1.8%, P < 0.01). The MR2* change in high dose iodixanol was approximately twice compared with the low dose (303% versus 133%, P < 0.01).
  
  
  CONCLUSIONS
  The viscosity of radio-contrast seems to play a more significant role than osmolality in terms of renal oxygenation changes as evaluated by BOLD MRI. Additionally, iodixanol induced a dose-dependent increase in renal medullary hypoxia.
authors: Department of Radiology/Center for Advanced Imaging, Northshore University Healthsystem, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA. lli2@northshore.org
authors: Lu-Ping
authors: LP
authors: Li
authors: Tammy
authors: T
authors: Franklin
authors: Hongyan
authors: H
authors: Du
authors: Maria
authors: M
authors: Papadopoulou-Rosenzweig
authors: Joann
authors: J
authors: Carbray
authors: Richard
authors: R
authors: Solomon
authors: Pottumarthi V
authors: PV
authors: Prasad
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000009:adverse effects / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D007674:Kidney Diseases / Q000097:blood* / Q000139:chemically induced* / Q000175:diagnosis; D008279:Magnetic Resonance Imaging; D008297:Male; D009994:Osmolar Concentration; D010100:Oxygen; D010101:Oxygen Consumption; D051381:Rats; D017207:Rats, Sprague-Dawley; D014283:Triiodobenzoic Acids / Q000009:adverse effects* / Q000737:chemistry*; D014783:Viscosity
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol; D010100:Oxygen