Student Poster Presentation #6 (Session 1)
DTI-based Network Analysis of APP/PS1 Mouse Brains with Age and
Gender
David Hike 1 , Scott Boebinger, Tara Palin and Samuel C. Grant
Chemical & Biomedical Engineering, FAMU–FSU College of Engineering, Florida State University
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Abstract
In this study, diffusion tensor imaging (DTI) is applied to the 5xFAD APP/PS1 double transgenic mouse model
of familial Alzheimer’s degeneration at multiple early time points with network theory analysis employed to
examine structural connectivity alterations as a function of age and gender compared to wild type controls. DTI
data was acquired with a multi-slice 2D spin echo using 18 diffusion encoding directions. Two to three brains
were imaged simultaneously with an in-plane resolution of 100x100 m and a slice thickness of 500 m. To
detect
-amyloid plaques, 3D images were acquired at 11.75 and 21.1 T using a true 3D gradient-recalled echo
sequence to provide an isotropic 25- m resolution in approximately 14.5 h. DTI data were analyzed using DSI
Studio 1 to generate diffusion streamlines. Locally and globally, structural connectivity was analyzed utilizing 13
regions of interest (ROIs) positioned in cortical regions and a single manually segmented node representative of
the hippocampus (Fig 1). Tracts were run to each individual node in order to derive quantifiable matrices that
correspond to neural graphs (Fig 2). The decrease in FA has been found to continually decrease as a function of
age. Current findings show a significant decrease in the FA in the temporal regions of the cortex in transgenic
models (Fig 3). Extracellular plaques detected at 21.1 T without contrast agents are localized in regions with FA
decreases (Fig 4). Least significant difference and one-way ANOVA were used to determine statistical
significance.
Figure 3: Decrease in FA of the
temporal region of AD samples when
compared to age matched controls.
Figure 1: Visual representation of AD/WT tracts
connectivity parameters and tracts at 1 and 6 months
old. The structural connectivity in the hippocampi is
investigated by quantifying distracted tracts that
connect to cortical nodes. Blue nodes indicate an
absence of connectivity between them and the
hippocampus. Note that the connectivity tends to be
impacted by both age and pathology. Nonetheless, AD
6 months samples exhibit less connectivity when
compared to their matching controls.
Figure 2: Weighted Degree in the 6-mon
AD Hippocampi shows significant decrease
when compared to 1 month WT and AD as
well as 6 month WT. The parietal area of
cortex shows a similar drop for 6-mon AD
compared to younger samples as well as the
age matching WT.
Figure 4: Plaques are visible in
5xFAD at 21.1 T with from T 2* -
weighted MRI at 25-µm resolution
compared to age- matched control.
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