Assessment of radiocontrast media induced renal vasoconstriction by color coded duplexsonography

Introduction: Changes in renal hemodynamics are suspected to be one of the major pathogenetic correlates in radiocontrast media-induced nephrotoxicity. We investigated whether color-coded duplex sonography is an appropriate method to document changes in intrarenal vascular resistance, after intravenous injection of the low-osmolar contrast material Iopamidol. Methods: Intrarenal arterial doppler wave forms were analyzed every minute after intravenous injection of 100 mL Iopamidol in 10 patients during a voiding cystourogram-procedure. The Resistive Index (RI) of each flow curve, reflecting intrarenal flow resistance, was calculated and compared to the mean of four RI measurements taken before contrast media application. Results: One minute after injection of Iopamidol the RI remained unchanged compared to the baseline standard of 0.70. In measurements obtained 2, 3,4, and 5 minutes after Iopamidol injection a statistically significant rise was seen: (minute 2. 0.74, p < 0.001/minute 3: 0.75, p = 0.001/minute 4: 0.72, p = 0.018/minute 5: 0.74, p = 0.031). During the further course, the resistive indices decreased progressively and showed no significant difference in comparison with the baseline standard value. Conclusion: Color coded duplex sonography is a simple method to detect changes in renal flow resistance after application of radiocontrast media. Based on our results, we believe that the analysis of intrarenal arterial doppler flow profiles constitutes an ideal method to investigate pathophysiologic mechanisms of radiocontrast media-induced nephrotoxicity, as well as pharmacological concepts in nephroprotectivity.