Longitudinal MRI Characterization of <i>T</i> ₁ and <i>T</i> ₂ Relaxation Times in an Amyloid Mouse Model of Alzheimer's Disease at 11.7 T

Longitudinal (T₁) and transverse (T₂) relaxation times measured by MRI are promising markers for assessing biological processes and disease pathology. In this study, we characterized the T₁ and T₂ relaxation times in the Tg2576 mouse model of Alzheimer's disease (N = 10) across ten time points, ranging from 3 to 14 months of age, using an 11.7 T MRI scanner. Genotype-dependent changes over time were observed in the thalamus, hypothalamus, and piriform cortex, suggesting that the rates of change in relaxation times within these regions may serve as potential markers for distinguishing Tg2576 mice from their wildtype (WT) counterparts. In addition, significant genotype differences were detected in the isocortex and hippocampus. These observations likely reflect the interplay between changes in tissue water content and the accumulation of amyloid plaques. To provide a reference for future MRI studies, we also calculated the average relaxation times over time points for WT mice. The mean T₁ values were 2036.3 ± 26.8 ms (isocortex), 2046.5 ± 28.7 ms (hippocampus), 1861.7 ± 22.2 ms (thalamus), 1897.8 ± 57.0 ms (hypothalamus), and 2099.7 ± 30.5 ms (piriform cortex). Corresponding T₂ values were 38.3 ± 0.5 ms (isocortex), 39.0 ± 0.2 ms (hippocampus), 35.4 ± 0.3 ms (thalamus), 36.9 ± 0.4 ms (hypothalamus), and 40.3 ± 0.3 ms (piriform cortex).