Precise Tracking of White Matter Integrity Following TBI in Densely Sampled Individuals
Poster No:
2360
Submission Type:
Abstract Submission
Authors:
Aishwarya Rajesh1, Ashley Meyer1, Jason Hassenstab1, Terrance Kummer1, Evan Gordon1, Nico Dosenbach1
Institutions:
1Washington University, St. Louis, MO
First Author:
Co-Author(s):
Introduction:
Traumatic brain injury (TBI) has the highest incidence of all common neurological disorders, with enduring, debilitating impairments to quality of life (Maas et al., 2022). Accumulating evidence suggests that the global pathology underlying TBI-related impairment is axonal injury. Axonal injury can be noninvasively detected by a magnetic resonance imaging technique known as diffusion tensor imaging (DTI; Hulkower et al., 2013). Fractional anisotropy (FA)- a DTI-derived measure that describes the asymmetry of water diffusion within white matter bundles-is a commonly used surrogate marker for axonal injury that may serve as a biomarker for TBI severity and outcomes. However, interpreting FA in the context of TBI is difficult because the trajectory of FA changes after TBI is unclear: FA has been reported to both decrease and increase following TBI (Adnan et al., 2013, Chiou et al., 2019). To improve the utility of FA as a biomarker of TBI, a more comprehensive study of FA changes over time is critical. Here, we tracked weekly changes in FA over 27 weeks in 3 participants with TBI using an extended-acquisition, tract-based approach. For the first time, we show a precise and detailed characterization of the longitudinal recovery of white matter integrity after TBI.
Methods:
Participant 1 identified as a 21yo female with pronounced right temporal subdural hematoma from a motor vehicle collision (MVC; GCS =15). She reported headaches, neck, and chest pain following injury. Participant 2 identified as a 31yo female with a right frontal subdural hematoma from an MVC. She reported headaches as well as pain/numbness in her left shoulder/arm following injury (GCS=14). Participant 3 identified as a 29 yo male who suffered a 10-foot fall. His CT scan revealed no obvious head trauma, but he reported persistent headaches and nausea symptoms following injury (GCS=13).
DTI images were collected weekly over 27 weeks beginning ~two weeks after hospital admission and concluding 6 months later. DTI images were processed using FSL's DTIfit (Jenkinson, 2012). 18 white matter tracts were identified in each participant using TRACULA (Yendiki et al., 2011). For each session, FA values were extracted from each tract. Across sessions, FA changes were modeled against time using both linear and quadratic fits, and adjusted R-squared values were used to determine the best fit. In each participant, a two-way ANOVA was performed to analyze the effect of time and tract on FA, using the model: FA~time + tract + time*tract. The main effect of time (indicating the global effect of TBI recovery) was the primary effect of interest.
DTI images were collected weekly over 27 weeks beginning ~two weeks after hospital admission and concluding 6 months later. DTI images were processed using FSL's DTIfit (Jenkinson, 2012). 18 white matter tracts were identified in each participant using TRACULA (Yendiki et al., 2011). For each session, FA values were extracted from each tract. Across sessions, FA changes were modeled against time using both linear and quadratic fits, and adjusted R-squared values were used to determine the best fit. In each participant, a two-way ANOVA was performed to analyze the effect of time and tract on FA, using the model: FA~time + tract + time*tract. The main effect of time (indicating the global effect of TBI recovery) was the primary effect of interest.
Results:
The ANOVA revealed a significant main effect of time in each participant (ps < 10-7). Post-hoc testing indicated that in Participant 1, 13 of 18 tracts showed a significant change in FA over time. 12 of these tracts showed a positive parabolic relationship, such that FA values initially declined (~3 months), and then increased with time until the last tracked timepoint. Variance explained by this parabolic relationship reached 71% in some tracts. In Participant 2, 7 of 18 tracts showed a significant change in FA over time, with 3 tracts following a similar parabolic path. For Participant 3, 9 of 18 tracts showed a significant change, with FA showing a linear decline with time.
·Trajectory of White Matter Integrity indexed by Fractional Anisotropy (FA) for Participant 01 with Traumatic Brain Injury (TBI).
Conclusions:
Across participants and tracts, changes in FA over time were generally described by positive parabolic relationships or linear decreases (which could be the initial stages of a positive parabolic effect). We speculate that the initial decline in FA may be associated with tract degeneration, and that the subsequent FA increase may reflect an adaptive neuroplasticity (Harris et al., 2016), enabling recovery to baseline. Together, this work significantly improves our understanding of recovery-related trajectories of a common neuroimaging marker of TBI, and thus may enable precise tracking of recovery processes in TBI patients.
Lifespan Development:
Lifespan Development Other
Modeling and Analysis Methods:
Connectivity (eg. functional, effective, structural) 2
Diffusion MRI Modeling and Analysis
Neuroanatomy, Physiology, Metabolism and Neurotransmission:
White Matter Anatomy, Fiber Pathways and Connectivity
Novel Imaging Acquisition Methods:
Diffusion MRI 1
Keywords:
Tractography
Other - Traumatic Brain Injury; Fractional Anisotropy; Longitudinal; Precision Neuroimaging
1|2Indicates the priority used for review
Provide references using author date format
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