Quantitative photoacoustic imaging using known chromophores as fluence marker

Quantitative Photoacoustic aims to recover optical absorption coefficients of chromophores in tissue by addressing challenges associated with spectral coloring and fluence variations. We propose an inversion framework incorporating a fluence marker, a reference chromophore with known optical properties, to improve the absorption coefficient recovery accuracy which we studied by simulation and experiment. The gradient based method, with and without fluence marker integration, was employed for optical inversion. The results demonstrated that the fluence marker method can mitigate spectral coloring and can quantitatively recover optical absorption spectra. The gradient based method, constrained with the fluence marker optimization, achieved greater accuracy and robustness across varying depths and tissue regions, compared to unconstrained inversion. This study highlights the potential for fluence marker-based inversion for applications in tissue characterization, such as imaging of carotid plaques, where precise quantification of optical properties is critical.