Effects of perfusion and vascular architecture on contrast dispersion: Validation in ex-vivo porcine liver under machine perfusion

Dynamic contrast enhanced ultrasound (DCE-US) enables imaging of cancer angiogenesis by quantification of perfusion and dispersion. Although increased perfusion may be found in areas of active angiogenesis due to increased demands for blood supply, decreased perfusion may be caused by the decreased efficiency and functionality, typical of cancer angiogenic microvasculature. Contrast dispersion, mainly determined by the flow profile in large vessels and by the multipath trajectories in the microvasculature, may thus represent a suitable alternative to characterize cancer angiogenesis. Based on a model of the contrast transport kinetics as a convective-dispersion process, several DCE-US methods have been proposed estimating dispersion for characterization of cancer angiogenic vasculature. Although dispersion imaging has shown promising in a clinical context, its physical link with variations in flow and vascular architecture has never been shown. The objective of this work is thus to investigate the influence of flow and underlying vascular architecture on the estimation of dispersion in an ex-vivo machine-perfused pig liver.