Impact of Real Liver Motion on HIFU Treatments: an in-vivo-data-based modeling

Abstract

Organs motion is a key component in the treatment of abdominal lesions by HIFU, since it may influence the efficacy and treatment time. Previous studies on HIFU treatments showed the effect of motor‐controlled translations applied to in vitro liver samples. In vivo organs motions are more complex and could lead to various effects on HIFU treatments. Here we report that a combined method can be used for simulating the effect of real in vivo motion on HIFU lesion in the liver. Sequences of ultrasound images were acquired in vivo during an open procedure on 4 pigs during breathing and apnea using a 12 MHz ultrasound imaging probe. Ultrasound correlation‐based methods were used to estimate liver motion using speckle tracking. These in vivo motion data were included in numerical simulations based on Bio Heat Transfer Equation for evaluating the influence of motion on treatments performed with a 3 MHz spherical HIFU transducer. Data acquired during breathing confirmed that liver motions were mainly encountered in the cranial‐caudal direction (f = 0.2 Hz, magnitude: 13.3±1.1 mm). Liver motions due only to cardiovascular activity were negligible (f = 0.96 Hz, magnitude <0.5 mm). When considering in vivo liver motion, simulated HIFU lesions were significantly modified (size, homogeneity) between control (no motion) and breathing samples. These results allow the estimation of the influence of effective liver motion on HIFU treatments. Additionally this combined method may be used to simulate the effectiveness of solutions suggested for correcting tissue motion during HIFU therapy.