The use of quantitative perfusion fluorometry to measure relative tumor and liver blood flow after transient microembolization

Optimal chemotherapy delivery to the tumor depends on regional drug concentration, tumor perfusion, tissue drug uptake, and metabolism. Modulation of tumor blood flow has been used to improve tumor response to treatment. Transient microembolization is one method to alter regional blood flow, but its effects on relative changes in tumor and liver blood flow have not been previously measured. This study used quantitative perfusion fluorometry (QPF) to evaluate blood flow distribution in liver and tumor before and after hepatic arterial infusion of degradable starch microspheres (DSMs) in 10 New Zealand white rabbits. QPF was compared with radioactive xenon-133 washout, an established method for measuring blood flow. Xenon-133 was injected intraparenchymally and the clearance rate was measured allowing calculation of relative blood flow. QPF was then used to measure liver and tumor blood flow in a hepatic VX-2 tumor model after hepatic artery injection of DSMs. Initial tumor blood flow was 55% of liver flow. DSMs produced a significant and transient decrease in hepatic blood flow that was decreased to 40% of baseline after 25 min. Changes in relative hepatic blood flow after DSMs as measured by QPF correlated strongly with results obtained by xenon-133 washout (R = 0.97, P < 0.01). Fluorometry's simplicity and reliability may be clinically useful to evaluate tumor blood flow characteristics.