Integrated spectral and depth compensation approach for optimizing oxygen saturation and total hemoglobin estimation in photoacoustic tomography for ovarian lesion diagnosis

Abstract. Significance Photoacoustic tomography (PAT) holds promise for non-invasive functional imaging in ovarian cancer diagnostics. However, accurate estimation of oxygen saturation (%sO2) and total hemoglobin concentration (THb) is hindered by wavelength- and depth-dependent fluence variations. Aim We aim to improve the accuracy and clinical utility of %sO2 and THb quantification in transvaginal ultrasound-guided PAT (US-PAT) by developing an integrated spectral and depth compensation (ISDC) method that corrects for both spectral distortion and depth-dependent attenuation. Approach We introduce a spectral compensation strategy derived from Monte Carlo simulations and integrate it with depth-wise fluence correction to construct the proposed ISDC method. The approach has been validated using phantoms with known optical properties and applied to clinical PAT data from 82 ovarian lesions (67 benign and 15 malignant). Diagnostic performance was evaluated using logistic regression and receiver operating characteristic analysis. Results In phantom experiments, ISDC improved %sO2 estimation accuracy compared with linear unmixing (LU) and enhanced uniformity of THb estimates across depth. In clinical data, ISDC has increased %sO2 values by ∼5% in both benign and malignant lesions, enhanced contrast of THb between malignant and benign lesion groups (mean THb ratio RTHb has increased from 1.4 to 1.9), and achieved higher classification performance (AUC = 0.93 versus 0.88 for LU) when combining %sO2 and THb features. Conclusions The ISDC approach significantly enhances the quantitative accuracy and diagnostic performance of PAT by compensating for both spectral and depth fluence variations within biological tissue. These improvements support the integration of ISDC into US-PAT systems for ovarian lesion characterization and future clinical applications.