Microbubble-enhanced HIFU therapy: Effect of exposure parameters on thermal lesion volume and temperature

Abstract

Microbubble agents have been shown to increase therapeutic effect of HIFU (high intensity focused ultrasound). In this work, the effects of treatment parameters on HIFU thermal lesion volume and temperature are investigated. Ex vivo tissues were treated with a 2 MHz HIFU beam in absence and presence of the Artenga® microbubbles at varying HIFU focal intensities (600-2400 W/cm 2), microbubble concentrations, and exposure durations (3-10 s). The temperature was measured at 1 mm from the focus using a K-type calibrated thermocouple. Thermal lesion volume was measured based on an ellipsoid model. Microbubbles increased the lesion volume and peak temperature achieved with HIFU. At the intensity of 2316 W/cm2, the lesion volume increased by two folds, and the peak temperature increased by 16°C with microbubbles. This effect depended on microbubble concentration, ultrasound intensity and exposure duration. Lower intensities and shorter exposure time durations were required at higher microbubble concentrations to ablate the tissue. It was concluded that the efficacy of the HIFU therapy in combination with microbubbles can be controlled through ultrasound and microbubble exposure parameters. © 2012 American Institute of Physics.