Renal artery stenosis in swine: feasibility of MR assessment of renal function during percutaneous transluminal angioplasty.

Abstract

To prospectively test--in a swine model of renal artery stenosis (RAS)--the hypothesis that magnetic resonance (MR) imaging can reveal changes in renal function at the time of percutaneous transluminal angioplasty (PTA). In this animal care and use committee-approved study, high-grade unilateral RAS was surgically induced in six pigs. MR imaging at 3.0 T was used for intraprocedural assessment of the anatomic and physiologic changes induced by x-ray-guided PTA. With use of MR imaging, changes in single-kidney glomerular filtration rate, extraction fraction, and renal blood flow were assessed during PTA. The arterial diameter of stenosis before and after PTA was assessed by using conventional digital subtraction angiography. Mean changes in functional and anatomic parameters were compared by using the Wilcoxon signed rank test (alpha = .05). At digital subtraction angiography, the mean percentage of stenosis was 69% +/- 10 (standard deviation) before PTA and 26% +/- 10 after PTA (P<.03). Mean pre- and post-PTA extraction fraction values were 0.11 +/- 0.03 and 0.19 +/- 0.06, respectively (P<.03). The mean single-kidney glomerular filtration rate before PTA, 19 mL/min +/- 13, increased to 41 mL/min +/- 33 after PTA (P<.03). There was no significant change in mean renal blood flow after PTA (P=.44). In swine, MR imaging can reveal changes in renal function after x-ray-guided PTA for unilateral RAS.