🤖 AI Summary
This study addresses the challenge of chromophore concentration estimation in spectral photoacoustic imaging, which is hindered by nonlinearity and ill-posedness. The authors propose SPOI-AE, a physics-informed neural network based on an autoencoder architecture, marking the first application of physics-informed deep learning to nonlinear spectral unmixing. By jointly modeling the photoacoustic generation and spectral unmixing processes within a unified framework, SPOI-AE enables end-to-end estimation of chromophore concentrations and tissue oxygen saturation without relying on linear assumptions or ground-truth labels. Evaluated on in vivo mouse lymph node data, SPOI-AE significantly outperforms conventional algorithms, yielding more accurate reconstructions. Simulations further confirm its high unmixing accuracy and demonstrate that the estimated parameters exhibit strong biological plausibility.
📝 Abstract
Accurate estimation of the relative concentrations of chromophores in a spectroscopic photoacoustic (sPA) image can reveal immense structural, functional, and molecular information about physiological processes. However, due to nonlinearities and ill-posedness inherent to sPA imaging, concentration estimation is intractable. The Spectroscopic Photoacoustic Optical Inversion Autoencoder (SPOI-AE) aims to address the sPA optical inversion and spectral unmixing problems without assuming linearity. Herein, SPOI-AE was trained and tested on \textit{in vivo} mouse lymph node sPA images with unknown ground truth chromophore concentrations. SPOI-AE better reconstructs input sPA pixels than conventional algorithms while providing biologically coherent estimates for optical parameters, chromophore concentrations, and the percent oxygen saturation of tissue. SPOI-AE's unmixing accuracy was validated using a simulated mouse lymph node phantom ground truth.