Assessment of Temporal Lobe Vasculature in Alzheimer’s Disease

Abstract

Alzheimer’s disease (AD) is the leading cause of dementia in the US (1) and the devasting impact of this grows in severity as our elderly population grows (2). AD causes pathological changes to both the brain tissue, in the form of atrophy (3), and the vasculature, in the form of increasing complexity such as increased branching and tortuosity (4). A previous work (4) has shown the cerebral macrovascular architecture changes over the whole brain, demonstrating increased tortuosity and abnormal branching of the vessels, as well as decreased diameter, however to the best of our knowledge, these changes have not been investigated in anatomical brain regions that have been shown to undergo atrophy with disease progression. In AD, the first site that atrophy and remodeling occurs in is the temporal lobe (5). In this work, we aim to assess changes in the vasculature occurring in the temporal lobe with AD and dementia. To assess these changes a multimodal registration pipeline was created using FSL to apply standardized labels generated from an atlas to Time-of-Flight Magnetic Resonance Angiography (TOF-MRA) scans. These were then used to mask the temporal lobar region of vessel segmentations, then a feature extraction step was performed to obtain the 1) total length, 2) number of branches, 3) maximum branch length, 4) average branch length, 5) total volume, 6) fractal dimension and 7) tortuosity for the left and right hemisphere. The results of this work show no significant changes in vascular morphology or symmetry in the temporal lobe macrovasculature for the selected cohort against age-matched healthy subjects; however, a larger cohort might show statistical significance in the changes across cognitive groups.