Establishing norms for age-related changes in proton T-1 of human brain tissue in vivo

The goal of this study was to determine the expected normal range of variation in spin-lattice relaxation time (T-1) of brain tissue in vivo, as a function of age. A previously validated precise and accurate inversion recovery method was used to map T-1 transversely, at the level of the basal ganglia, in a study population of 115 healthy subjects (ages 4 to 72; 57 male and 58 female). Least-squares regression analysis shows that T-1 varied as a function of age in pulvinar nucleus (R-2 = 56%), anterior thalamus (R-2 = 51%), caudate (R-2 = 50%), frontal white matter (R-2 = 47%), optic radiation (R-2 = 39%), putamen (R-2 = 36%), genu (R-2 = 22%), occipital white matter (R-2 = 20%) (all p < 0.0001), and cortical gray matter (R-2 = 53%) (p < 0.001). There were no significant differences in T-1 between men and women. T-1 declines throughout adolescence and early adulthood, to achieve a minimum value in the fourth to sixth decade of life, then T-1 begins to increase. Quantitative magnetic resonance imaging provides evidence that brain tissue continues to change throughout the lifespan among healthy subjects with no neurologic deficits. Age-related changes follow a strikingly different schedule in different brain tissues; white matter tracts tend to reach a minimum T-1 value, and to increase again, sooner than do gray matter tracts. Such normative data may prove useful for the early detection of brain pathology in patients. (C) 1997 Elsevier Science Inc.