T and T measurements of the neonatal brain at 7 T.

PURPOSE

To determine the expected range of NMR relaxation times (T and T) in the neonatal brain at 7 T.

METHODS

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 T and T mapping protocols were used to provide measurements in white matter, cortex, cerebellum, and deep gray matter. Automatic image segmentation of a separate T-weighted brain volume was used to define regions of interest for analysis.

RESULTS

Linear regression was used to estimate relaxation times at term equivalent age (40 weeks postmenstrual age). 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. 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.

CONCLUSIONS

We describe neonatal brain tissue and age-specific T and T relaxation values at 7 T. The presented values differ substantially from both adult values at 7 T and neonate values measured at lower field strengths, and will be essential for pulse-sequence optimization for neonatal studies.