title: Longitudinal Assessment of Renal Perfusion and Oxygenation in Transplant Donor-Recipient Pairs Using Arterial Spin Labeling and Blood Oxygen Level-Dependent Magnetic Resonance Imaging.
abstract: OBJECTIVE
  The aims of this study were to assess renal function in kidney transplant recipients and their respective donors over 2 years using arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) and to prospectively evaluate the effect of losartan on functional MRI measures in recipients.
  
  
  METHODS
  The study included 15 matched pairs of renal transplant donors and recipients. Arterial spin labeling and BOLD MRI of the kidneys were performed on donors before transplant surgery (baseline) and on both donors and recipients at 3 months, 1 year, and 2 years after transplant. After 3 months, 7 of the 15 recipients were prescribed 25 to 50 mg/d losartan for the remainder of the study. A linear mixed-effects model was used to evaluate perfusion, R2*, estimated glomerular filtration rate, and fractional excretion of sodium for changes across time or associated with losartan treatment.
  
  
  RESULTS
  In donors, cortical perfusion in the remaining kidney decreased by 50 ± 19 mL/min per 100 g (11.8%) between baseline and 2 years (P < 0.05), while cortical R2* declined modestly by 0.7 ± 0.3 s-1 (5.6%; P < 0.05). In transplanted kidneys, cortical perfusion decreased markedly by 141 ± 21 mL/min per 100 g (34.2%) between baseline and 2 years (P < 0.001), while medullary R2* declined by 1.5 ± 0.8 s-1 (8.3%; P = 0.06). Single-kidney estimated glomerular filtration rate increased between baseline and 2 years by 17.7 ± 2.7 mL/min per 1.73 m (40.3%; P < 0.0001) in donors and to 14.6 ± 4.3 mL/min per 1.73 m (33.3%; P < 0.01) in recipients. Cortical perfusion at 1 and 2 years in recipients receiving 25 to 50 mg/d losartan was 62 ± 24 mL/min per 100 g higher than recipients not receiving the drug (P < 0.05). No significant effects of losartan were observed for any other markers of renal function.
  
  
  CONCLUSIONS
  The results suggest an important role for noninvasive functional monitoring with ASL and BOLD MRI in kidney transplant recipients and donors, and they indicate a potentially beneficial effect of losartan in recipients.
authors.affiliation: From the Departments of *Medical Physics, †Medicine, ‡Surgery, §Radiology, ∥Obstetrics and Gynecology, and ¶Biomedical Engineering, University of Wisconsin, Madison, WI.
authors.forename: David J
authors.initials: DJ
authors.lastname: Niles
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Artz
authors.forename: Arjang
authors.initials: A
authors.lastname: Djamali
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Sadowski
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Grist
authors.forename: Sean B
authors.initials: SB
authors.lastname: Fain
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D007677:Kidney Function Tests / Q000379:methods; D016030:Kidney Transplantation; D008137:Longitudinal Studies; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D012077:Renal Artery / Q000473:pathology / Q000503:physiopathology*; D012079:Renal Circulation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels; D014019:Tissue Donors; D066027:Transplant Recipients
chemical_list: D013113:Spin Labels; D010100:Oxygen