Ultrasound-guided Photoacoustic image Annotation Toolkit in MATLAB (PHANTOM) for preclinical applications

Abstract

Depth-dependent fluence-compensation in photoacoustic (PA) imaging is paramount for accurate quantification of chromophores from deep tissues. Here we present a user-friendly toolkit named PHANTOM (PHotoacoustic ANnotation TOolkit for MATLAB) that includes a graphical interface and assists in the segmentation of ultrasound-guided PA images. We modelled the light source configuration with Monte Carlo eXtreme and utilized 3D segmented tissues from ultrasound to generate fluence maps to depth compensate PA images. The methodology was used to analyze PA images of phantoms with varying blood oxygenation and results were validated with oxygen electrode measurements. Two preclinical models, a subcutaneous tumor and a calcified placenta, were imaged and fluence-compensated using the PHANTOM toolkit and the results were verified with immunohistochemistry. The PHANTOM toolkit provides scripts and auxiliary functions to enable biomedical researchers not specialized in optical imaging to apply fluence correction to PA images, enhancing accessibility of quantitative PAI for researchers in various fields.

Vascular regional analysis unveils differential responses to anti-angiogenic therapy in pancreatic xenografts through macroscopic photoacoustic imaging

“…As the transducer moves throughout the tumor volume to obtain a 3D scan, separate simulations were done for each transducer location and compiled to generate the resulting fluence map. More detailed information on the simulation geometry and parameters used for Monte Carlo parameters can be obtained from Sweeney et al [85]…”

“…Fluence compensation was performed using Monte Carlo simulations utilizing the Monte Carlo eXtreme (MCX) package for MATLAB [83,84] and the PHotoacoustic ANnotation TOolkit for MATLAB (PHANTOM) [85]. Fluence compensation maps were generated for and applied to all PA images used in analysis.…”