Differentiation of vascular characteristics using contrast enhanced ultrasound imaging

Ultrasound contrast imaging is used to image the macro- and micro-vasculature. The aim of our investigation was to distinguish between different types of vessels such as veins, arteries and microvasculature within the limits of the spatial resolution of contrast enhanced ultrasound imaging. The highly vascularised ovine ovary was used as a biological model. Perfusion of the ovary with SonoVue (ultrasound contrast agent) was recorded with a Philips iU22 ultrasound scanner in contrast imaging mode. One ewe was treated with prostaglandin to induce anti-angiogenesis. After scanning each ovary was removed and fixed. Tissue sections were stained, and vessels sized and counted. Time-intensity curves for different regions of interest were obtained, and flow parameters calculated. Parametric maps of the whole imaging plane were generated for 2x2 pixel regions of interest. Vessel classification into four types (arteries, veins, medium-sized vessels and micro-vessels) was achieved by the assessment of different flow parameters. Further development may enable automation of the technique as an efficient way of monitoring vessels in a clinical setting using currently available scanners.