Reconstruction of Endoscopic Photoacoustic Tomographic Images for Attenuating Acoustic Tissues: A Preliminary Study

Biological endoscopic photoacoustic tomography (EPAT) Has been rapidly developed in the past decades as a hybrid functional imaging modality with multi-physics coupling. The acoustic inhomogeneity of biological tissues results in acoustic reflection, scattering, diffusion and absorption, thus the attenuated photoacoustic signals measured by the detector. The idealized assumptions on the acoustic homogeneity usually lead to reconstructed images with reduced quality and imaging depth. This paper focuses on a preliminary study of EPAT image reconstruction accounting for acoustic attenuation. The correlation equation related to ideal and measured photoacoustic signals is deduced. The equation is then solved by using singular value decomposition (SVD) to recover the approximation of the ideal signals from the measured signals. Finally, the cross-sectional images of optical distribution are reconstructed from the ideal signals. Numerical results indicate that this method can effectively reduce image artifacts caused by acoustic attenuation and improve image focusing. Comparison results suggest that it outperforms the method of correcting the frequency-dependent attenuation which requires the prior knowledge about attenuation coefficients of tissues.