Longitudinal changes in hippocampal transverse relaxation time are associated with amyloid deposition

Motivation: Transverse relaxation time (T2) of the hippocampus could be an early biomarker of Alzheimer's disease (AD). However, it remains unclear how hippocampal T2 changes in normal aging and whether it correlates with cortical amyloid deposition. Goal(s): We aim to explore hippocampal T2 as an indicator of tissue integrity changes linked to amyloid accumulation in a cognitively normal aging cohort. Approach: Quantitative T2 of the bilateral hippocampus was measured longitudinally and compared to amyloid PET markers. Results: We show that increased left hippocampal T2 is significantly associated with amyloid deposition in this preclinical AD cohort, providing unique microstructural information on top of volumetric measures. Impact: Hippocampal T2 changes indicate potential neural inflammation and compromised tissue integrity related to Aβ deposition in preclinical AD. Quantitative T2 may be a valuable biomarker for identifying these subtle microstructural changes before brain macroscopic alterations and symptom onset.