title: MR imaging assessment of changes in renal function with renal artery stent placement in swine.
abstract: OBJECTIVE
  To prospectively test the hypothesis that magnetic resonance (MR) imaging can detect changes in renal function at the time of renal artery stent placement in a swine model of renal artery stenosis (RAS).
  
  
  METHODS
  In this animal care and use committee-approved study, hemodynamically significant (>50%) RAS was surgically induced in six pigs. MR imaging was employed for assessment of the anatomic and physiologic changes induced by fluoroscopically guided stent placement. With MR imaging, we assessed changes in renal blood flow (RBF), extraction fraction (EF), and single-kidney glomerular filtration rate (skGFR) during the procedure. Arterial diameter stenosis before and after stent placement was assessed with x-ray digital subtraction angiography (DSA). Mean changes in functional and anatomic parameters were compared with the Wilcoxon matched-pairs test, with an alpha level of 0.05.
  
  
  RESULTS
  There was no significant change in mean RBF after stent deployment (P=.44). Mean EF increased from 0.19+/-0.08 before stent placement to 0.31+/-0.17 after stent placement (P=.16). Mean skGFR measurements were 25 mL/min+/-16 before stent placement and 41 mL/min+/-28 after stent placement (P<.05). According to x-ray DSA measurements, mean stenosis measurements were 60%+/-12% before stent placement and 24%+/-16% after stent placement (P<.02).
  
  
  CONCLUSIONS
  In swine, MR imaging can detect immediate changes in renal function after radiographically guided stent placement for unilateral RAS. This functional MR technique may have applications in the setting of hybrid MR/x-ray DSA procedure suites.
authors.affiliation: Department of Radiology, Northwestern University Feinberg School of Medicine, 448 East Ontario Street, Suite 700, Chicago, IL 60611, USA.
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Park
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Rhee
authors.forename: Ty A
authors.initials: TA
authors.lastname: Cashen
authors.forename: Wanyong
authors.initials: W
authors.lastname: Shin
authors.forename: Scott A
authors.initials: SA
authors.lastname: Resnick
authors.forename: James A
authors.initials: JA
authors.lastname: Gehl
authors.forename: Brian E
authors.initials: BE
authors.lastname: Schirf
authors.forename: Dingxin
authors.initials: D
authors.lastname: Wang
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Larson
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Carroll
authors.forename: Reed A
authors.initials: RA
authors.lastname: Omary
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D001807:Blood Vessel Prosthesis; D005260:Female; D005919:Glomerular Filtration Rate; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007668:Kidney / Q000098:blood supply / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012077:Renal Artery / Q000503:physiopathology / Q000601:surgery; D012078:Renal Artery Obstruction / Q000503:physiopathology* / Q000601:surgery*; D015607:Stents; D013552:Swine