Experimental evaluation of lesion prediction modelling in the presence of cavitation bubbles: Intended for high-intensity focused ultrasound prostate treatment

Abstract

The accuracy of high-intensity focused ultrasound (HIFU) lesion prediction modelling was evaluated for a truncated spherical transducer designed for prostate cancer treatment The modelling adapted the bio heat transfer equation (BHTE) to take into account the activity of cavitation bubbles generated during HIFU exposure. This modelling was used to predict the lesions produced by three different transducer geometries: fixed-focus, concentric-ring and 1.5D phased-array. Lesions were predicted for different ultrasound exposure conditions close to those used in prostate cancer treatment. Twenty-one in vitro and nine in vitro experiments were performed on pig liver to validate the accuracy of the predictions. A good match was found between the predicted and experimental lesion shapes. Lesion dimensions (maximum depth and length, area at the centre of the lesion or central surface area) were measured on experimental and predicted lesions. The central surface area was predicted by the model with a range of error of 0.15-6.5% for in vitro tests and 0.97-9% in vivo. For comparison, BHTE without bubbles had a range of error of 0.4-55.5% (in vitro) and 9-25.5% (in vivo). The model should be accurate enough to predict HIFU lesions under ultrasound exposure conditions used in prostate cancer treatment.

Improved visualization of high-intensity focused ultrasound lesions

“…The occurrence of cavitation during HIFU will alter lesion shape, size and position in comparison to purely thermally generated lesions (Chavrier et al 2000;Curiel et al 2004). The role of gas-body generated harmonics versus non-linear propagation in the observations reported here is thus of significance because generation of gas bodies may not be desirable from the standpoint of control of lesion growth.…”

Heart ablation using a planar rectangular high intensity ultrasound transducer and MRI guidance

“…There are many studies that predicted the size of the lesions as function of power and time (for example [54,56,57]). For example Damianou and Hynynen [56] evaluated the lesion size in dog muscle in vitro, Fagi et al [57] performed a similar study in bovine in liver and Curiel et al [54] have evaluated the lesion size in prostate.…”

“…For example Damianou and Hynynen [56] evaluated the lesion size in dog muscle in vitro, Fagi et al [57] performed a similar study in bovine in liver and Curiel et al [54] have evaluated the lesion size in prostate. Therefore, for each application (in our case heart) and for every transducer (in our case planar) the lesion size has to be evaluated both using simulation and experimental models.…”

Enhancement of High-Intensity Focused Ultrasound Heating by Short-Pulse Generated Cavitation

“…The volumetric oscillation of bubbles increases ultrasonic energy dissipation in the vicinity of the bubbles through three mechanisms such as acoustic radiation, thermal, and viscous damping, which resulted in the enhanced heating effect. The effect of bubble-enhanced ultrasonic heating has been investigated experimentally [11][12][13][14][15][16][17][18][19][20][21][22][23][24] and numerically [25,26]. Although increased heat depositions were obtained using microbubbles in the previous research, distorted coagulation regions or temperature distribution were observed, such as tad-pole shaped [12,22,24] or pre-focal [13,19,[24][25][26] heating regions.…”