MR assessment of the brain maturation during the perinatal period:: Quantitative T2 MR study in premature newborns

The purpose of our study is to trace in vivo and during the perinatal period, the brain maturation process with exhaustive measures of the T-2 relaxation time values. We also compared regional myelination progress with variations of the relaxation time values and of brain signal. T-2 relaxation times were measured in 7 healthy premature newborns at the post-conceptional age of 37 weeks, using a Carr-Purcell-Meiboom-Gill sequence (echo time 60 to 150 ms), on a 2.35 Tesla Spectre-Imaging MR system. A total of T-2 measures were defined for each subject within the brain stem, the basal ganglia and the hemispheric gray and white matter. The mean and standard deviation of the T-2 values were calculated for each location. Regional T-2 values changes and brain signal variations were studied. In comparison to the adult ones, the T-2 relaxation time values of both gray and white matter were highly prolonged and a reversed ratio between gray and white matter was found. The maturational phenomena might be regionally correlated with a T-2 value shortening. Significant T-2 variations in the brainstem (p < 0.02), the mesencephalon (p < 0.05), the thalami (p < 0.01), the lentiform nuclei (p < 0.01) and the caudate nuclei (p < 0.02) were observed at an earlier time than they were visible on T-2-weighted images. In the cerebral hemispheres, T-2 values increased from the occipital white matter to parietal, temporal and frontal white matter (p < 0.05) and in the frontal and occipital areas from periventricular to subcortical white matter (p < 0.01). Maturational progress was earlier and better displayed with T-2 measurements and T-2 mapping. During the perinatal period, the measurements and analysis of T-2 values revealed brain regional differences not discernible with T-2-weighted images. It might be a more sensitive indicator for assessment of brain maturation. (C) 1999 Elsevier Science Inc.