T1 and T2 measurements of the neonatal brain at 7 T

To determine the expected range of NMR relaxation times (T1 and T2) in the neonatal brain at 7 T.PURPOSETo determine the expected range of NMR relaxation times (T1 and T2) in the neonatal brain at 7 T.Data were acquired in a total of 40 examinations on infants in natural sleep. The cohort included 34 unique subjects with postmenstrual age range between 33 and 52 weeks and contained a mix of healthy individuals and those with clinical concerns. Single-slice T1 and T2 mapping protocols were used to provide measurements in white matter, cortex, cerebellum, and deep gray matter. Automatic image segmentation of a separate T2-weighted brain volume was used to define regions of interest for analysis.METHODSData were acquired in a total of 40 examinations on infants in natural sleep. The cohort included 34 unique subjects with postmenstrual age range between 33 and 52 weeks and contained a mix of healthy individuals and those with clinical concerns. Single-slice T1 and T2 mapping protocols were used to provide measurements in white matter, cortex, cerebellum, and deep gray matter. Automatic image segmentation of a separate T2-weighted brain volume was used to define regions of interest for analysis.Linear regression was used to estimate relaxation times at term equivalent age (40 weeks postmenstrual age). T 1 40 wk $$ {T}_1^{40 wk} $$ with 95% confidence intervals was measured to be 2933 [2893, 2972] ms in white matter; 2653 [2604, 2701] ms in cerebellum; and 2486 [2439, 2532] ms in basal ganglia. T 2 40 wk $$ {T}_2^{40 wk} $$ was estimated as 119 [116, 121] ms in white matter, 99 [96, 102] ms in cerebellum, and 90 [89, 92] ms in basal ganglia. Most tissue-relaxation times showed a significant negative correlation with postmenstrual age, with the strongest correlation seen in cerebellum.RESULTSLinear regression was used to estimate relaxation times at term equivalent age (40 weeks postmenstrual age). T 1 40 wk $$ {T}_1^{40 wk} $$ with 95% confidence intervals was measured to be 2933 [2893, 2972] ms in white matter; 2653 [2604, 2701] ms in cerebellum; and 2486 [2439, 2532] ms in basal ganglia. T 2 40 wk $$ {T}_2^{40 wk} $$ was estimated as 119 [116, 121] ms in white matter, 99 [96, 102] ms in cerebellum, and 90 [89, 92] ms in basal ganglia. Most tissue-relaxation times showed a significant negative correlation with postmenstrual age, with the strongest correlation seen in cerebellum.We describe neonatal brain tissue and age-specific T1 and T2 relaxation values at 7