Characterization of Lesion Formation and Bubble Activities during High Intensity Focused Ultrasound Ablation using...

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Acoustic Physics

Background:

• High-intensity focused ultrasound (HIFU) enables thermal tissue ablation, but precise monitoring of temperature and tissue status is crucial for successful outcomes.
• Current methods often rely on temperature measurements to predict and track the ablation process, necessitating further investigation into temperature-tissue interaction.

Purpose of the Study:

• To investigate the relationship between temperature changes and tissue coagulation/bubble formation during HIFU ablation.
• To identify temperature-derived parameters for accurate monitoring of HIFU-induced lesions and overheating.

Main Methods:

• Experiments using ex vivo porcine myocardium with infrared thermography and bright-field imaging during HIFU application.
• Analysis of spatiotemporal temperature evolution to correlate with lesion formation, overheating, and bubble generation.
• Development and validation of criteria based on temperature change rates and spatial distribution for lesion identification.

Main Results:

• A significant increase in temperature change rate correlated with lesion formation (99.1% accuracy).
• Asymmetric temperature distribution indicated overheating and bubble generation (90.9% accuracy).
• Cumulative equivalent minutes at 43 °C (CEM43) for lesion formation was determined to be 170 min.

Conclusions:

• Spatiotemporal temperature analysis using IR imaging provides valuable insights into HIFU-induced irreversible tissue changes.
• Derived temperature parameters can effectively monitor HIFU treatment, distinguishing between normal lesions and overheating.
• The findings support the use of temperature monitoring for enhanced precision and safety in HIFU therapies.