Quantitative ultrasound molecular imaging for antiangiogenic therapy monitoring

The link between cancer growth and angiogenesis has led to the development of new techniques for cancer imaging and therapy. Ultrasound molecular imaging permits the visualization of angiogenesis by use of novel targeted ultrasound contrast agents, (tUCA), consisting of ligand-bearing microbubbles designed to specifically bind molecular angiogenic expressions. Discrimination between bound and free microbubbles is crucial to quantify angiogenesis. Currently, the degree of binding is assessed by the differential targeted enhancement, requiring the application of a destructive burst in the late phase (usually 5-10 min after injection) to isolate the signal from bound microbubbles. Recently, we proposed a novel method for quantitative assessment of binding by modeling the microbubble binding kinetics during the tUCA first pass, reducing the acquisition time to 1 min with no need for a destructive burst. The feasibility of the method for angiogenesis imaging was shown in prostate tumor-bearing rats. In this work, we evaluate the proposed method for monitoring the response to angiogenic treatment in human colon cancer xenograft-bearing mice.