Renal blood flow changes induced with endothelin-1 and fenoldopam mesylateat quantitative Doppler US: Initial results in a canine study

PURPOSE: To evaluate quantitative Doppler ultrasonography (US) for assessin g renal blood flow changes induced with endothelin-1 (ET-1) and fenoldopam mesylate in conscious dogs. MATERIALS AND METHODS: A blood flow probe was surgically implanted around t he renal artery in eight adult dogs. Color and power Doppler US images were acquired in conscious restrained dogs during intravenous infusion of ET-1 and fenoldopam mesylate. Simultaneous with imaging, blood flow through the renal artery was measured with the implanted probe. The color level of the images within the region representing the kidney was analyzed to derive flo w indices. These indices were compared with direct-flow measurements. RESULTS: The flow indices, color-weighted flow area (CWFA), and percentage of area of color, derived from color and power Doppler US images, correlate d linearly with direct flow. The mean color level of color and power Dopple r US images correlated weakly with direct flow. Pre- versus postinfusion CW FA decreased with all ET-1 infusions (P less than or equal to .032). Infusi on of fenoldopam mesylate increased CWFA in all cases (P less than or equal to .032). CONCLUSION: Quantitative Doppler US enabled successful measurement of the f low changes induced with ET-1 and fenoldopam mesylate. Quantitative Doppler US is potentially useful as a noninvasive surrogate endpoint in evaluating the action of various therapeutic agents.