Modelling the temperature evolution of bone under high intensity focused ultrasound

Area of Science:

• Biomedical Engineering
• Medical Physics
• Oncology

Background:

• Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) effectively manages pain from bone metastases.
• Current MR-HIFU treatments for bone lack direct temperature monitoring, relying on adjacent soft tissue data.
• This limitation hinders precise temperature control and treatment efficacy in bone metastasis ablation.

Purpose of the Study:

• To develop and validate a computational model for accurate spatial temperature evolution in bone during MR-HIFU.
• To address the lack of MR-based thermometry for bone tissue.
• To improve the safety and effectiveness of MR-HIFU for bone metastasis treatment.

Main Methods:

• A two-part computational model was developed: ray-tracing for heat production and Pennes' bio-heat equation for temperature calculation.
• The model incorporates shear waves at the bone interface and detailed geometrical factors.
• Model validation was performed against theoretical approximations and MR-HIFU phantom experiments.

Main Results:

• The model accurately predicted temperature evolution in bone and adjacent tissues during sonication.
• Simulated temperatures showed good agreement with both theoretical models and experimental phantom data.
• The study quantified the impact of shear waves on heat distribution within bone.

Conclusions:

• The developed computational model provides a reliable method for simulating MR-HIFU temperature distribution in bone.
• This tool can enhance the planning and execution of MR-HIFU treatments for bone metastases.
• It paves the way for improved pain management in patients with skeletal metastases.