Quantitative assessment of peripheral vasculature using a 3D bimodal photoacoustic and ultrasound foot scanner

Peripheral vascular disease (PVD) is a narrowing of the arteries in the extremities that might result in amputation when left untreated. The conventional ways to diagnose PVD are vascular imaging techniques such as ultrasound (US) Doppler, computed tomography (CT) angiography, and magnetic resonance angiography, which generally can only visualize large vessels or require contrast agents. Photoacoustic (PA) imaging could be a promising agent-free, highresolution modality to visualize vessels and be applied in various clinical studies. We have previously demonstrated an agent-free multi-structural photoacoustic (PA) and US peripheral angiography technique using contour scanning. To reduce the effect of the optical fluence, we compensated the PA images using the background PA signals that represent optical attenuation in the tissue. To evaluate its capability to provide functional information of the vasculature, we demonstrated an intentional blood flow occlusion with a pressure cuff and observed the changes in the quantification metrics. From the experiments, we confirmed the potential of the technique for providing a diagnostic evaluation of the peripheral vasculature.