Photoacoustic vector tomography for deep haemodynamic imaging

Imaging deep haemodynamics non-invasively remains a quest. Although optical imaging techniques can be used to measure blood flow, they are generally limited to imaging within similar to 1 mm below the skin's surface. Here we show that such optical diffusion limit can be broken through by leveraging the spatial heterogeneity of blood and its photoacoustic contrast. Specifically, successive single-shot wide-field photoacoustic images of blood vessels can be used to visualize the frame-to-frame propagation of blood and to estimate blood flow speed and direction pixel-wise. The method, which we named photoacoustic vector tomography (PAVT), allows for the quantification of haemodynamics in veins more than 5 mm deep, as we show for regions in the hands and arms of healthy volunteers. PAVT may offer advantages for the diagnosis and monitoring of vascular diseases and for the mapping of the function of the circulatory system. Successive single-shot wide-field photoacoustic images can be used to estimate the speed and direction of blood flow at more than 5 mm deep from the skin's surface.

Automated summary

Photoacoustic vector tomography (PAVT) is a method that uses successive single-shot wide-field photoacoustic images to estimate blood flow speed and direction at depths greater than 5 mm from the skin's surface. It breaks the optical diffusion limit and allows for the quantification of haemodynamics in deep veins.