Nonlinear iterative perturbation scheme with simplified spherical harmonics (SP₃) light propagation model for quantitative photoacoustic tomography

Abstract

When using quantitative photoacoustic tomography (q‐PAT) reconstruction to recover the optical absorption coefficients of tissue, the commonly used diffusion equation has several limitations in the case of the objects that have small geometries and high‐absorption or low‐scattering areas. Furthermore, the conventional perturbation reconstruction strategy is unsatisfactory when the target tissue containing large heterogeneous features. We herein present a modified q‐PAT implementation that employs the higher‐order photon migration model achieving the tradeoff between mathematical rigidity and computational efficiency. Besides, a nonlinear iterative method is proposed to obtain the perturbations of optical absorption considering the updating of the sensitivity matrix in calculating the fluence perturbations. Consequently, the distribution of tissue optical properties can be recovered in a robust way even if the targets with high absorption are included. The proposed approach has been validated by simulation, phantom and in vivo experiments, exhibiting promising performances in image fidelity and quantitative feasibility for practical applications.

Recent advances in deep-learning-enhanced photoacoustic imaging

“…They then designed a dual-path network based on U-Net (QPAT-Net) to reconstruct images of the absorption coefficient for deep tissues. The QPAT-Net outperformed the previous QPAT method 128 in simulation, ex vivo , and in vivo , with more accurate absorption information and relatively few errors.…”

A Data Self-Calibration Method Based on High-Density Parallel Plate Diffuse Optical Tomography for Breast Cancer Imaging

“…The target was made of a combination of intralipid (20%) and India ink. The concentration of intralipid (20%) and Indian ink required for the experiment can be determined according to the empirical formula and the absorbance measured by the spectrometer, respectively ( 36 ). The optical properties of both targets were μ a = 0.03mm -1 , = 1mm -1 .…”

Quantitative photoacoustic tomography: modeling and inverse problems

“… 30 – 34 In QPAT, utilizing simplified spherical harmonics approximation has been utilized. 35 , 36 Numerical approximation of the RTE with Henyey–Greenstein phase function can be challenging if scattering is highly forward dominated. Therefore, approximations to the RTE that takes into account forward-peaked scattering analytically have been proposed.…”

“…Furthermore, hybrid models coupling nonscattering and/or low-scattering medium with highly scattering medium have been developed 30 – 34 In QPAT, utilizing simplified spherical harmonics approximation has been utilized 35 , 36 . Numerical approximation of the RTE with Henyey–Greenstein phase function can be challenging if scattering is highly forward dominated.…”