971-54 A Non-invasive Method of Visually Assessing Renal Perfusion Using a Newly Developed Intravenous Ultrasound Contrast

Abstract

Present methods of quantifying renal artery blood flow (RABF) in renovascular disease require either radionuclide techniques or invasive delivery of radiographic or ultrasound contrast. Perfluoropropane is a gas routinely used for intraocular injections which, when sonicated with dextrose albumin (PESDA). produces microbubbles with prolonged survival in blood. We hypothesized, therefore, that this prolonged ultrasound contrast effect could be utilized to non-invasively evaluate RABF and perfusion, Accordingly, we gave intravenous injections (IVI) of PESDA (0.06 cc/kg) to seven dogs while imaging with an external 4.5 MHz linear array transducer RABF was monitored using a Transonic Doppler probe placed around the renal artery. Contrast two-dimensional enhancement was quantified off-line. Both echo and color Doppler enhancement were also qualitatively graded as 0 = no enhancement, 1+ = mild, 2+ = marked enhancement. Following all 36 (100%) IVI of PESDA, there was 2+ contrast ultrasound enhancement of the renal cortex. A linear correlation existed between Doppler renal artery flow and peak renal cortex videointensity follOWing IV PESDA (r = 0.65, P < 0.001), Color Doppler signals were also enhanced following IV PESDA, and resulted in excellent visualization of the main renal artery as well as segmental and lobar arteries. When renal artery stenosis was induced to decrease RABF to less than 10% of baseline, the segmental and lobar arteries were not visualized with color Doppler following IV PESDA, and peak renal cortex videointensity was reduced from 26 ± 10 to 15 ± 8 units (p < 0.05). These data demonstrate that renal artery and cortical blood flow abnormalities can be detected using intravenous PESDA. This ultrasound contrast agent could be a new non-invasive method to detect renal artery stenosis or abnormal renal perfusion.