Prolonged T*2 values in newborn versus adult brain: Implications for fMRI studies of newborns.

The neonatal brain possesses higher water content, lower macromolecular concentration, and reduced synaptic density than is found in the brain of a 1-year-old child. Changes in MRI characteristics of brain such as relaxation times accompany rapid changes in brain during early postnatal development. It was hypothesized that T(*)(2) values found in newborns would be significantly higher than those found in 9-month-old children and adults as measured at 1.5 T. Spoiled gradient echo measurements of T(*)(2) within the brains of newborns, 9-month-olds, and adults confirmed this hypothesis. The results have implications with regard to functional MRI studies in newborns since, in general, BOLD signal optimization is achieved when echo times TE are set equal to the T(*)(2) values of the tissue of interest. Since significantly longer T(*)(2) values are found in newborns, it is suggested that the TE values employed for fMRI studies of newborns should be increased to maximize BOLD signal intensity changes and improve the overall reliability of fMRI results in newborns. Copyright 2004 Wiley-Liss, Inc.