Temperature measurement in human fat with T2 imaging

Abstract

Purpose To develop a method for noninvasive T2-based thermometry that enables estimation of the in vivo temperature in adipose tissues at both 1.5T and 3T field strengths. Materials and Methods A total of 27 apparent T2-temperature measurement sets were performed on 13 human abdominal adipose tissue samples using an inversion prepared dual-echo single-slice sequence for apparent T2 estimation. The measurements were performed on Ingenia 1.5T and 3.0T scanners and Achieva 1.5T and 3.0T scanners. The apparent T2-values were measured at 4°C temperature intervals during heating from 21 to 45°C and cooling to 21°C. A two-parameter exponential fit was used to estimate the apparent T2 to temperature dependency on a scanner-to-scanner basis. Results In the temperature range evaluated (21-45°C), the apparent T2 relaxation times increased from an average of ∼ 100 msec to 190 msec at1.5T and an average of ∼130 msec to 220 msec at 3T. The measured T2-relaxation times followed the calibration curve with a median absolute error of 0.37°C and maximum error of 1.7°C in 12 of the 13 samples, with the outlier having a notably different appearance upon visual inspection prior to measurement. Conclusion Changes in apparent T2 relaxation time has the potential to be used for accurately estimating local temperature within in vivo subcutaneous fat.