Kidney blood flow occlusion by acoustic droplet vaporization

Acoustic droplet vaporization (ADV) has been introduced with the potential application of tumor treatment via occlusion and subsequent necrotic ischemia in the targeted region. In this study an entire organ was the target for occlusion. Lepus kidneys were chosen for bubble production and subsequent vascular occlusion of the organ. The left kidney was externalized and an imaging array plus a single element transducer were positioned with direct access to the kidney´s vasculature and renal artery. Filtered droplet emulsions (diameter <5 um) were injected during insonification of the renal artery and the extent of blood flow reduction by ADV was compared to the untreated right side kidney. Blood flow before and after each treatment was measured using fluorescently stained PVC spheres (diameter 15 um) injected intra-arterially (IA) into the heart´s left ventricle. Flow cytometry analysis of kidney tissue samples allowed the estimation of regional blood flow inside the tissue samples. Bubble production was possible for IV as well as IA administered emulsions. A maximum regional blood flow reduction of >95% (91% for total organ) was found for occlusion produced by bubbles from ADV of IA injected droplet emulsions. Hyperechogenicity from ADV of IA injections was monitored for approximately one hour.