Improved photoacoustic-based oxygen saturation estimation with SNR-regularized local fluence correction

As photoacoustic (PA) imaging makes its way into the clinic, accuracy of PA-based metrics becomes increasingly important. To address this need, a method combining finite- element-based local fluence correction (LFC) with signal-to-noise- ratio (SNR) regularization was developed and validated to accurately estimate oxygen saturation (SO2) in tissue. With data from a Vevo LAZR system, performance of our LFC approach was assessed in ex vivo blood targets (37.6% – 99.6% SO2) and in vivo rat arteries. Estimation error of absolute SO2 and change in SO2 reduced from 10.1% and 6.4%, respectively, without LFC to 2.8% and 2.0%, respectively, with LFC, while accuracy of the LFC method was correlated with the number of wavelengths acquired. This work demonstrates the need for SNR-regularized LFC to accurately quantify SO2 with PA imaging.