Evaluating the Effects of Water Balloons on High-Intensity Focused Ultrasound for Treating Uterine Fibroids

In the treatment of uterine fibroids with ultrasound-guided high-intensity focused ultrasound (HIFU), water balloons are considered to be a valuable aid for improving safety and efficiency. However, the water balloons worsen the pathway for acoustic transmission, causing degraded performance both in ultrasound therapy and in ultrasound imaging. This study was aimed at establishing a protocol to evaluate the effects of the water balloon. Simulations and experiments were carefully conducted to quantitatively investigate the effects of water ballons on the efficiency of HIFU energy delivery and on the quality of ultrasound guiding images. More specifically, HIFU-induced temperature increases in the focal region, together with spatial resolution, contrast and signal-to-noise ratio in the ultrasound guiding images, were compared under the conditions with and without the water balloon. Experiment results revealed that the use of water balloons led to decreases in temperature up to 10ºC within the focal region in some specific situations, but the quality of the guiding images was relatively less affected. The study provided knowledge on what influence the water balloon could have in ultrasound-guided HIFU treatment; it also established a practical and standardized evaluation scheme for further optimizing the water balloon, for example, its material and internal liquid compositions. This study can potentially help improve the efficiency and safety of treating uterine fibroids with ultrasound-guided HIFU systems.