Dr. Kimberly R. Pechman Profile

Dr. Kimberly R. Pechman

at Vanderbilt Univ. Medical Ctr.

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Publications (5)

SPIE Journal Paper | 17 April 2024 Open Access

Empirical assessment of the assumptions of ComBat with diffusion tensor imaging

Michael Kim, Chenyu Gao, Leon Cai, Qi Yang, Nancy Newlin, Karthik Ramadass, Angela Jefferson, Derek Archer, Niranjana Shashikumar, Kimberly Pechman, Katherine Gifford, Timothy Hohman, Lori Beason-Held, Susan Resnick, Stefan Winzeck, Kurt Schilling, Panpan Zhang, Daniel Moyer, Bennett Landman

JMI, Vol. 11, Issue 02, 024011, (April 2024) https://doi.org/10.1117/12.10.1117/1.JMI.11.2.024011

KEYWORDS: Silver, Diffusion tensor imaging, Error analysis, Diffusion, Statistical analysis, Biological samples, Reliability, Data modeling, Magnetic resonance imaging, Voxels

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Proceedings Article | 2 April 2024 Poster + Paper

Evaluation of mean shift, ComBat, and CycleGAN for harmonizing brain connectivity matrices across sites

Hanliang Xu, Nancy Newlin, Michael Kim, Chenyu Gao, Praitayini Kanakaraj, Aravind Krishnan, Lucas Remedios, Nazirah Mohd Khairi, Kimberly Pechman, Derek Archer, Timothy Hohman, Angela Jefferson, Ivana Isgum, Yuankai Huo, Daniel Moyer, Kurt Schilling, Bennett Landman

Proceedings Volume 12926, 129261X (2024) https://doi.org/10.1117/12.3005563

KEYWORDS: Matrices, Brain, Scanners, Alzheimer disease, Biological research, Anatomy

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Proceedings Article | 2 April 2024 Poster + Paper

Learning site-invariant features of connectomes to harmonize complex network measures

Nancy Newlin, Praitayini Kanakaraj, Thomas Li, Kimberly Pechman, Derek Archer, Angela Jefferson, Bennett Landman, Daniel Moyer

Proceedings Volume 12930, 129302E (2024) https://doi.org/10.1117/12.3009645

KEYWORDS: Education and training, Brain, Scanners, Diffusion, Alzheimer disease, Diffusion magnetic resonance imaging, Data modeling, Biological imaging, Matrices, Magnetic resonance imaging

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Proceedings Article | 2 April 2024 Presentation + Paper

Investigating interactions between subcortical structure, fMRI vigilance signals, and cognition in healthy and pathological aging

Kate Wang, Sarah Goodale, Derek Doss, Deepak Gupta, Katherine Gifford, Kimberly Pechman, Timothy Hohman, Dario Englot, Angela Jefferson, Catie Chang

Proceedings Volume 12930, 129300Q (2024) https://doi.org/10.1117/12.3000729

KEYWORDS: Functional magnetic resonance imaging, Brain, Cognition, Neuroimaging

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Proceedings Article | 3 April 2023 Poster + Paper

Comparing voxel- and feature-wise harmonization of complex graph measures from multiple sites for structural brain network investigation of aging

Nancy Newlin, Leon Cai, Tianyuan Yao, Derek Archer, Kurt Schilling, Timothy Hohman, Kimberly Pechman, Angela Jefferson, Andrea Shafer, Susan Resnick, Bennett Landman

Proceedings Volume 12464, 124642B (2023) https://doi.org/10.1117/12.2653947

KEYWORDS: Diffusion weighted imaging, Scanners, Brain, Statistical analysis, Neuroimaging, Voxels, Cognitive modeling, Alzheimer's disease

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Complex graph theory measures of brain structural connectomes derived from diffusion weighted images (DWI) provide insight into the network structure of the brain. Further, as the number of available DWI datasets grows, so does the ability to investigate associations in these measures with major biological factors, like age. However, one key hurdle that remains is the presence of scanner effects that can arise from different DWI datasets and confound multisite analyses. Two common approaches to correct these effects are voxel-wise and feature-wise harmonization. However, it is still unclear how to best leverage them for graph-theory analysis of an aging population. Thus, there is a need to better characterize the impact of each harmonization method and their ability to preserve age related features. We investigate this by characterizing four complex graph theory measures (modularity, characteristic path length, global efficiency, and betweenness centrality) in 48 participants aged 55 to 86 from Baltimore Longitudinal Study of Aging (BLSA) and Vanderbilt Memory and Aging Project (VMAP) before and after voxel- and feature-wise harmonization with the Null Space Deep Network (NSDN) and ComBat, respectively. First, we characterize across dataset coefficients of variation (CoV) and find the combination of NSDN, and ComBat causes the greatest reduction in CoV followed by ComBat alone then NSDN alone. Second, we reproduce published associations of modularity with age after correcting for other covariates with linear models. We find that harmonization with ComBat or ComBat and NSDN together improves the significance of existing age effects, reduces model residuals, and qualitatively reduces separation between datasets. These results reinforce the efficiency of statistical harmonization on the feature-level with ComBat and suggest that harmonization on the voxel-level is synergistic but may have reduced effect after running through the multiple layers of the connectomics pipeline. Thus, we conclude that feature-wise harmonization improves statistical results, but the addition of biologically informed voxel-based harmonization offers further improvement.

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