title: BOLD quantified renal pO2 is sensitive to pharmacological challenges in rats.
abstract: Blood oxygen level-dependent (BOLD) MRI has been effectively used to monitor changes in renal oxygenation. However, R2* (or T2*) is not specific to blood oxygenation and is dependent on other factors. This study investigates the use of a statistical model that takes these factors into account and maps BOLD MRI measurements to blood pO2.
  
  
  
  Spin echo and gradient echo images were obtained in six Sprague-Dawley rats and R2 and R2* maps were computed. Measurements were made at baseline, post-nitric oxide synthase inhibitor (L-NAME), and post-furosemide administration. A simulation of each region was performed to map R2' (computed as R2*-R2) to blood pO2.
  
  
  
  At baseline, blood pO2 in the outer medulla was 30.5 ± 1.2 mmHg and 51.9 ± 5.2 mmHg in the cortex, in agreement with previous invasive studies. Blood pO2 was found to decrease within the outer medulla following L-NAME (P < 0.05) and increase after furosemide (P < 0.05). Blood pO2 in the cortex increased following furosemide (P < 0.05).
  
  
  
  Model-derived blood pO2 is sensitive to pharmacological challenges, and baseline pO2 is comparable to literature values. Reporting pO2 instead of R2* could lead to a greater clinical impact of renal BOLD MRI and facilitate the identification of hypoxic regions. Magn Reson Med 78:297-302, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors: Biomedical Engineering, Northwestern University, Evanston, Illinois, USA.
authors: Jon
authors: J
authors: Thacker
authors: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors: Jeff L
authors: JL
authors: Zhang
authors: Department of Radiology/Center for Advanced Imaging, NorthShore University HealthSystem, Evanston, Illinois, USA.
authors: Tammy
authors: T
authors: Franklin
authors: Department of Radiology/Center for Advanced Imaging, NorthShore University HealthSystem, Evanston, Illinois, USA.|Department of Radiology, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA.
authors: Pottumarthi
authors: P
authors: Prasad
mesh_terms: D000818:Animals; D005665:Furosemide / Q000008:administration & dosage; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007668:Kidney / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000378:metabolism*; D007677:Kidney Function Tests / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D005665:Furosemide; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester
keywords: BOLD; oxygen saturation of hemoglobin; oxygenation; pO2; renal