Microwave thermal imaging: initial in vivo experience with a single heating zone

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Thermal Therapy

Background:

• Hyperthermia cancer treatment requires real-time temperature monitoring for effective planning.
• Current methods lack non-invasive temperature feedback, limiting hyperthermia's clinical use.
• Microwave tomographic imaging shows promise for correlating electrical conductivity with temperature changes.

Purpose of the Study:

• Validate a non-invasive microwave tomographic thermal imaging system in vivo.
• Assess the system's ability to monitor temperature during hyperthermia in small animals.
• Establish correlation between imaged conductivity and actual temperature for clinical integration.

Main Methods:

• A microwave tomographic imaging system was adapted for small animal use within a CT scanner.
• Pigs underwent hyperthermia with a heated saline tube in the abdomen.
• Microwave data (300-1000 MHz) was collected, and images were reconstructed.
• Saline conductivity was analyzed against controlled temperature variations.

Main Results:

• The imaging system successfully visualized the heated saline tube in vivo.
• Recovered saline conductivity demonstrated a linear relationship with controlled temperature.
• Difference imaging confirmed the temperature-conductivity correlation.

Conclusions:

• The non-invasive microwave imaging system can accurately recover in vivo temperature.
• This technology is a crucial step towards integrating real-time thermal feedback into clinical hyperthermia.
• Further validation is needed before widespread clinical application.