Temperature measurement in human fat with T2 imaging

PurposeTo develop a method for noninvasive T-2-based thermometry that enables estimation of the in vivo temperature in adipose tissues at both 1.5T and 3T field strengths. Materials and MethodsA total of 27 apparent T-2-temperature measurement sets were performed on 13 human abdominal adipose tissue samples using an inversion prepared dual-echo single-slice sequence for apparent T-2 estimation. The measurements were performed on Ingenia 1.5T and 3.0T scanners and Achieva 1.5T and 3.0T scanners. The apparent T-2-values were measured at 4 degrees C temperature intervals during heating from 21 to 45 degrees C and cooling to 21 degrees C. A two-parameter exponential fit was used to estimate the apparent T-2 to temperature dependency on a scanner-to-scanner basis. ResultsIn the temperature range evaluated (21-45 degrees C), the apparent T-2 relaxation times increased from an average of approximate to 100 msec to 190 msec at 1.5T and an average of approximate to 130 msec to 220 msec at 3T. The measured T-2-relaxation times followed the calibration curve with a median absolute error of 0.37 degrees C and maximum error of 1.7 degrees C in 12 of the 13 samples, with the outlier having a notably different appearance upon visual inspection prior to measurement. ConclusionChanges in apparent T-2 relaxation time has the potential to be used for accurately estimating local temperature within in vivo subcutaneous fat. J. Magn. Reson. Imaging 2016;43:1171-1178.