Temperature Dependency of T1 Relaxation Time in Unfixed and Fixed Human Brain Tissue

MR relaxation times of most tissues are ex-pected to depend on temperature which can impact find-ings in post mortem MRI or MRI based thermometry. The purpose of this study was to investigate the exact tem-perature dependency of the T1 relaxation in different structures in unfixed and fixed human brain samples. Following autopsy, coronal brain slices from five de-ceased subjects underwent MRI at 3T in a temperature range between 4°C and 37°C. T1 showed a linear depend-ency on temperature with the highest temperature coeffi-cient in the cortex (17 ms/°C) and the lowest in the white matter (3ms/°C). The fixation of the tissue lowered T1 and additionally the temperature coefficient in all regions investigated. The temperature coefficients obtained in this study serve as reference for thermometry and for correct-ing quantitative post mortem MRI.