SO 2 quantification of rat HCC tumors using fluence-corrected photoacoustic imaging

Spectroscopic photoacoustic (sPA) can estimate blood oxygen saturation (SO 2 ), which has been shown to correlate with hypoxia, and therefore could improve cancer diagnosis and treatment monitoring. However, accurate quantification of SO 2 is often not straightforward as local fluence varies significantly at depth due to wavelength-dependent optical scattering and absorption. Additionally, assessing the quality of an SO2 estimate is not trivial as deep-lying (i.e., centimeter-order depth) PA data tends to be signal-limited, and SNR can vary substantially with wavelength for a particular voxel. This work implements an SNR-based thresholding approach combined with FEM-based local fluence correction to more accurately estimate SO 2 in a rat model of hepatocelluar carcinoma (HCC).