Temperature measurement in human fat with T2 imaging

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Therapeutic Monitoring

Background:

• Noninvasive temperature monitoring is crucial for various medical applications, including hyperthermia treatments and understanding metabolic processes.
• Magnetic resonance imaging (MRI) offers potential for noninvasive thermometry, but accurate methods for specific tissues like adipose tissue are needed.
• Previous methods often lack precision or are limited to specific field strengths.

Purpose of the Study:

• To develop and validate a noninvasive T2-based thermometry technique for estimating in vivo temperature in human abdominal adipose tissue.
• To assess the feasibility of this method at both 1.5T and 3T MRI field strengths.
• To establish a reliable calibration curve for T2 relaxation time as a function of temperature in adipose tissue.

Main Methods:

• Utilized an inversion-prepared dual-echo single-slice sequence for apparent T2 estimation in 13 human abdominal adipose tissue samples.
• Performed measurements across a temperature range of 21°C to 45°C and back to 21°C at 4°C intervals.
• Employed a two-parameter exponential fit for scanner-specific T2-temperature dependency calibration on 1.5T and 3T MRI scanners.

Main Results:

• Apparent T2 relaxation times demonstrated a clear temperature dependency, increasing from ~100-130 msec at 21°C to ~190-220 msec at 45°C across both field strengths.
• The developed method achieved high accuracy, with a median absolute error of 0.37°C and a maximum error of 1.7°C in 12 out of 13 samples.
• The calibration curve proved robust, with minimal deviation observed in most tissue samples.

Conclusions:

• Changes in apparent T2 relaxation time can accurately estimate local temperature within in vivo subcutaneous fat.
• This T2-based thermometry method shows significant potential for noninvasive temperature monitoring in adipose tissue.
• The technique is validated for use at both 1.5T and 3T MRI systems, broadening its clinical applicability.