Photoacoustic Imaging and Main Lobe Width Analysis for Enhancing Microwave Ablation Monitoring of Liver Tissue

Microwave ablation (MWA) is a minimally invasive technique for treating hepatic tumors, necessitating precise monitoring to ensure treatment efficacy and minimize damage to surrounding tissues. This study explores the potential of photoacoustic imaging (PAI) in monitoring MWA by examining ex vivo porcine liver tissues. In this study, a comprehensive analysis of photoacoustic signals was performed to compare the main lobe width (MLW) between ablated and normal regions in porcine liver tissue. Histological staining with succinate dehydrogenase (SDH) and shear wave elastography (SWE) were employed to validate the changes in tissue elasticity after ablation. The analysis demonstrated a notable reduction in the MLW of the average A-lines in ablated tissues compared to non-ablated regions (p<0.01). This reduction, attributed to increased tissue density and enhanced elasticity, indicates accelerated sound propagation in thermally ablated areas, which then serve as a critical parameter for mapping tissue characteristics. The reconstruction of the MLW distribution successfully delineated the ablated regions, which was consistent with the results of SDH staining and SWE. In addition, MLW-based imaging exhibited higher spatial resolution compared to SWE. Incorporating MLW analysis into PAI may be a promising strategy to improve the accuracy and effectiveness of MWA monitoring in clinical settings.