International Journal of Nephrology pharmacologic stimuli in animal models and in human sub- jects with promising results [53–60]. In some studies CEU has been superior to color and power Doppler US examina- tion in determining the cause of AKI [61]. While B mode US can provide information on structure of the kidneys, addition of ultrasound contrast agents has the potential of providing additional information on the pattern and quan- tity of regional and total RBF [61]. Once approved for clinical use in humans, CEU may be of great value in the work up of cases suspicious of CRS since altered renal hemodynamics are thought to be the cause of reduced GFR in these cases. 5. Conclusion Ultrasound based imaging of the heart (echocardiography) and the kidney are the methods of choice in the work up of cases suspicious of CRS. US imaging is safe, noninvasive and widely available. It provides valuable information on the structure and function of the heart and the structure of the kidney. 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