The effects on thermal lesion shape and size from bubble clouds produced by acoustic droplet vaporization.
BACKGROUND
Bubbles formed by acoustic droplet vaporization (ADV) have proven to be an effective method for significant enlargement of the thermal lesions produced by high intensity focused ultrasound (HIFU). We investigated the influences of bubble cloud shape and droplet concentration on HIFU thermal lesions, as these relate to the ADV technique.


METHODS
Unlike previous studies where the droplets were simultaneously vaporized with the HIFU exposure for thermal lesion formation, droplets were vaporized by pulse wave (PW) ultrasound prior to continuous wave (CW) ultrasound heating in this experimental study. Under different experimental conditions, we recorded and quantified by the image processing methods the morphology and size of the bubble clouds created and the corresponding thermal lesions formed.


RESULTS
The results demonstrated that different ADV droplet concentrations produced a variety of thermal lesion shapes and sizes. The lesion volume could be increased using PW ultrasound followed by CW exposure, especially for higher droplet concentrations, e.g. 3.41 × 106/mL yielded a tenfold increase over that seen using CW alone.


CONCLUSION
These findings could lead to optimization of HIFU therapy by selecting a bubble forming strategy and droplet concentrations, especially using lower ultrasound powers which is desirable in clinical applications.
['Xin|Ying|Y|', 'Zhang|Aili|A|http://orcid.org/0000-0002-7150-1422', 'Xu|Lisa X|LX|', 'Fowlkes|J Brian|JB|']
D000162:Acoustics D003198:Computer Simulation D004867:Equipment Design D005466:Fluorocarbons D005740:Gases D057086:High-Intensity Focused Ultrasound Ablation D006358:Hot Temperature D008055:Lipids D045423:Microbubbles D019047:Phantoms, Imaging D011312:Pressure D012815:Signal Processing, Computer-Assisted D014159:Transducers D014463:Ultrasonography D014835:Volatilization
Thermal lesions Bubble cloud Acoustic droplet vaporization (ADV) HIFU ablation