Objectives: T1 relaxometry is a promising tool for the assessment of microstructural changes during brain ageing. Previous cross-sectional studies demonstrated increasing T1 values in white and decreasing T1 values in grey matter over the lifetime. However, these findings have not yet been confirmed on the basis of a longitudinal study. In this longitudinal study over 7 years, T1 relaxometry was used to investigate the dynamics of age-related microstructural changes in older healthy subjects.
Methods: T1 mapping was performed in 17 healthy subjects (range 51-77 years) at baseline and after 7 years. Advanced cortical and white matter segmentation was used to determine mean T1 values in the cortex and white matter.
Results: The analysis revealed a decrease of mean cortical T1 values over 7 years, the rate of T1 reduction being more prominent in subjects with higher age. T1 decreases were predominantly localized in the lateral frontal, parietal and temporal cortex. In contrast, mean white matter T1 values remained stable.
Conclusions: T1 mapping is shown to be sensitive to age-related microstructural changes in healthy ageing subjects in a longitudinal setting. Data of a cohort in late adulthood and the senescence period demonstrate a decrease of cortical T1 values over 7 years, most likely reflecting decreasing water content and increased iron concentrations.
Key points: • T1 mapping is sensitive to age-related microstructural changes in a longitudinal setting. • T1 decreases were predominantly localized in the lateral frontal, parietal and temporal cortex. • The rate of T1 reduction was more prominent in subjects with higher age. • These changes most likely reflect decreasing cortical water and increasing iron concentrations.
Keywords: Ageing; Cerebral cortex; Quantitative magnetic resonance imaging; T1 relaxation; White matter.