Three-dimensional spatial and temporal temperature imaging in gel phantoms using backscattered ultrasound

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Acoustics

Background:

• Thermal therapies require precise monitoring of heat distribution for optimal outcomes.
• Current ultrasound temperature imaging is limited by 2D limitations and complex tissue properties.
• Inability to monitor heat deposition leads to suboptimal thermal therapy delivery and tissue necrosis.

Purpose of the Study:

• To develop and validate a 3D spatial and temporal ultrasound temperature estimation technique.
• To track the evolution of heat deposition within a treatment volume noninvasively.
• To assess the potential for image guidance in thermal therapies.

Main Methods:

• Developed a 3D ultrasound-based temperature estimation technique.
• Used an alginate-based gel phantom for experimental validation.
• Tracked echo arrival time shifts caused by temperature-dependent changes in speed of sound and thermal expansion.
• Compared ultrasound temperature estimates with embedded thermocouple measurements.

Main Results:

• The 3D ultrasound technique successfully tracked heat deposition in a gel phantom.
• Experimental validation showed good agreement between ultrasound estimates and thermocouple measurements (rms difference = 0.12°C, max difference = 0.24°C) for temperature rises up to ~10°C.
• The technique demonstrated accurate spatial and temporal temperature monitoring.

Conclusions:

• The developed 3D ultrasound temperature estimation technique shows promise for image guidance in thermal therapies.
• It can potentially determine the location of the therapeutic focal spot and assess the extent of the heated region.
• This noninvasive method could improve the precision and efficacy of thermal treatments.