Relationship Between Aging and T1 Relaxation Time in Deep Gray Matter: A Voxel-Based Analysis

Purpose: To investigate age-related changes in T-1 relaxation time in deep gray matter structures in healthy volunteers using magnetization-prepared 2 rapid acquisition gradient echoes (MP2RAGE). Materials and Methods: In all, 70 healthy volunteers (aged 20-76, mean age 42.6 years) were scanned at 3T magnetic resonance imaging (MRI). A MP2RAGE sequence was employed to quantify T-1 relaxation times. After the spatial normalization of T-1 maps with the diffeomorphic anatomical registration using the exponentiated Lie algebra algorithm, voxel-based regression analysis was conducted. In addition, linear and quadratic regression analyses of regions of interest (ROIs) were also performed. Results: With aging, voxel-based analysis (VBA) revealed significant T-1 value decreases in the ventral-inferior putamen, nucleus accumbens, and amygdala, whereas T-1 values significantly increased in the thalamus and white matter as well (P < 0.05 at cluster level, false discovery rate). ROI analysis revealed that T-1 values in the nucleus accumbens linearly decreased with aging (P=0.0016), supporting the VBA result. T-1 values in the thalamus (P < 0.0001), substantia nigra (P=0.0003), and globus pallidus (P < 0.0001) had a best fit to quadratic curves, with the minimum T-1 values observed between 30 and 50 years of age. Conclusion: Age-related changes in T-1 relaxation time vary by location in deep gray matter.