Mitigating the unicity problem in quantitative photoacoustic imaging using ultrasound blood flow imaging, a simulation study

<i>Objective.</i>Quantitative photoacoustic (PA) imaging aims at recovering optical properties in optically turbid media. Here, we aim to recover uniqueness of the solution in absorption and scattering coefficient in a single illumination and wavelength setting.<i>Approach.</i>By considering a numerical tissue model composed of optically contrasted regions surrounded by blood vessels, we combine PA imaging with ultrasound power Doppler (UPD). We show that quantitative absorption coefficients inside the blood vessels can be derived from UPD, serving as a prior for a radiance Monte Carlo inverse model.<i>Main results.</i>We show that using this vascular imaging prior mitigates the non-uniqueness issue, providing quantitative reconstructions of absorption and scattering even in the absence of background or blood absorption prior information. We generalize to unresolved capillary beds by degrading the resolution of UPD and PA.<i>Significance.</i>Since dual PA-ultrasound systems are already widespread, this approach could become an essential brick of quantitative PA imaging.