Impact of focused ultrasound on the cellular network of liver tissue: a new perspective for thermal lesion detection

<i>Objective.</i>The noninvasive characterization of soft tissue microstructure remains challenging and has a significant clinical impact on diagnosis and therapy monitoring. During high-intensity focused ultrasound (HIFU) treatments, coagulation necrosis is accompanied by mechanical changes. The objective of this work is to use the anisotropy arising at the cellular level as a new biomarker for treatment evaluation.<i>Approach.</i>We demonstrate that HIFU induces anisotropic alterations in the cellular architecture of liver tissue, which are detectable through the angular dependence of the backscattering coefficient (BSC). Also,<i>in vivo</i>experiments reveal a distinct anisotropic histological pattern localized in the HIFU-treated region.<i>Main results.</i>We show that the degree of anisotropy deduced from BSC measurements is correlated with the histological observations. Moreover, anisotropy increases with delivered energy, providing a quantitative link between treatment parameters and tissue response.<i>Significance.</i>These findings establish BSC anisotropy as a previously unexplored signature of thermal lesions, offering a promising approach for monitoring and feedback in thermal therapeutic ultrasound applications. This breakthrough could open the door to next-generation imaging tools, accelerating the widespread adoption of this highly effective therapeutic modality.