Assessment of the effect of radio contrast media on resistive index of renal artery by color doppler sonography.

Renal ischemia and direct toxic effect of contrast media are the main confounding causes of contrast-induced nephropathy (CIN). The effect of different contrast mediums on the resistance of renal artery is quite unclear. The aim of the present study was to assess the resistive index (RI) changes of renal segmental artery in color Doppler duplex sonography after injection of two different contrast mediums: iodixanol and iohexol. The RI of the renal segmental artery of 62 randomly chosen patients, with a normal baseline renal function, was calculated using color-coded Doppler sonography before and five minutes after bolus injection of two different contrast mediums. Thirty-one patients were administered 50 mL of iodixanol (Visipaque) and 31 patients were administered 50 mL of iohexol (Omnipaque) during intravenous urogram procedures. The RI results were analyzed and compared in two groups using two-tailed t-test. The mean RI of renal segmental artery increased significantly after administration of contrast media (mean +/- SD 0.61 +/- 0.046 vs 0.58 +/- 0.042; p< 0.001). The mean change of RI was 0.0387 +/- .00552 (mean +/- SE) in the setting of iohexol injection and 0.0216 +/- .00423 (mean +/- SE) five minutes after administration of iodixanol (p= 0.017). Both non-ionic iso-osmolar dimeric iodixanol and low-osmolar iohexol increase the renal artery resistance, but the changes are more dramatic with iohexol, suggesting better tolerance with iodixanol.