High-intensity focused ultrasound (HIFU) modeling: in vitro validation and integration into patient-specific planning tool

This study aims at developing and experimentally validate a three-dimensional numerical model designed to predict acoustic propagation and thermal effects during High-Intensity Focused Ultrasound (HIFU) therapy, in order to support patient-specific treatment planning. A 3D time-domain simulation was implemented using the k-Wave toolbox, capturing both acoustic wave propagation and thermal effects. Validation was performed using five tissue-mimicking phantoms with distinct acoustic and thermal properties, each tested under three different HIFU exposure conditions. Lesion dimensions were assessed longitudinally and transversely in both simulations and experiments, and spatial concordance was quantified by evaluating the overlap between simulated and experimental lesions. Simulated longitudinal lesion extents fell within the interquartile range of experimental data in four out of nine phantom-condition combinations with a maximum absolute error of 3.14 mm while transverse dimensions in three out of nine with maximum absolute error equal to 4.16 mm. Spatial overlap between simulated and experimental lesions reached a maximum of 92%. Simulations on phantoms required approximately 4 min, while patient-specific cases completed in about 7 min, accurately capturing heterogeneous tissue characteristics and bone interfaces. In scenarios involving rib intersection, a 40% reduction in focal pressure was observed, leading to significant smaller lesions. The validated 3D simulation, integrated into a planning platform, reliably predicts HIFU ablation zones and focal shifts, showing strong agreement with experimental data and delivering results within clinically feasible times.