Measurement of Healthy Adult Brain Temperature Using ¹H Magnetic Resonance Spectroscopy Thermometry

The purpose of this study is to measure the brain temperature (T_br) by using ¹H magnetic resonance spectroscopy (¹H MRS) thermometry and investigate its age and gender differences in healthy adults. The brain temperature was further compared with the body temperature (T_bo) to investigate the possible existence of brain-body temperature gradient (∆T).

A total of 80 subjects were included in this study. ¹H MRS data were collected on a 3.0T MR scanner using Point Resolved Selective Spectroscopy (PRESS) sequence. Voxels were positioned in the right frontal (RF) lobe and left frontal (LF) lobe, respectively. The temperature of each voxel was calculated by chemical shift difference (∆δ) between H₂O and NAA which was obtained by LCModel software. The average temperature of bilateral frontal lobe voxels was defined as T_br for each subject. The average forehead temperature was acquired before MR scanning, defined as T_bo, in this study. The difference between T_br and T_bo, denoted as the brain-body temperature gradient (∆T), was calculated. Age and gender characteristics of T_br, ∆T and T_bo were analyzed.

T_br (38.51 ± 0.59℃) was higher than T_bo (36.47 ± 0.26℃) (P < 0.05). Negative correlations were observed between T_br and age (r = -0.49, P < 0.05) and between ∆T and age (r = -0.44, P < 0.05), whereas no correlation existed between T_bo and age (r = -0.03, P = 0.79).

Our observation demonstrated that the brain temperature, derived from ¹H MRS thermometry, is significantly higher than the body temperature, indicating the existence of a brain-body temperature gradient, and the brain temperature gradually decreases with age.