Advanced neuroimaging applied to veterans and service personnel with traumatic brain injury: state of the art and potential benefits

Abstract

Traumatic brain injury (TBI) remains one of the most prevalent forms of morbidity among Veterans and Service Members, particularly for those engaged in the conflicts in Iraq and Afghanistan. Neuroimaging has been considered a potentially useful diagnostic and prognostic tool across the spectrum of TBI generally, but may have particular importance in military populations where the diagnosis of mild TBI is particularly challenging, given the frequent lack of documentation on the nature of the injuries and mixed etiologies, and highly comorbid with other disorders such as post-traumatic stress disorder, depression, and substance misuse. Imaging has also been employed in attempts to understand better the potential late effects of trauma and to evaluate the effects of promising therapeutic interventions. This review surveys the use of structural and functional neuroimaging techniques utilized in military studies published to date, including the utilization of quantitative fluid attenuated inversion recovery (FLAIR), susceptibility weighted imaging (SWI), volumetric analysis, diffusion tensor imaging (DTI), magnetization transfer imaging (MTI), positron emission tomography (PET), magnetoencephalography (MEG), task-based and resting state functional MRI (fMRI), arterial spin labeling (ASL), and magnetic resonance spectroscopy (MRS). The importance of quality assurance testing in current and future research is also highlighted. Current challenges and limitations of each technique are outlined, and future directions are discussed.

Ubiquinol treatment for TBI in male rats: Effects on mitochondrial integrity, injury severity, and neurometabolism

“…We did not detect differences in the brain concentration of any MRS neurochemical between groups. Given that MRS‐detected neurochemicals are reported to be sensitive in vivo biomarkers of tissue pathology (Oz et al, ; Wilde et al, ), and our mitochondrial, apoptosis, and serum assays all suggest a beneficial effect of ubiquinol, we found the lack of neurochemical differences between groups to be surprising. However, mitochondrial and apoptosis assays were completed in cortical tissue, whereas the ROI for MRS mostly assessed subcortical tissue to avoid primary cortical damage (Figure ), which could contribute MR susceptibility artifacts from bleeding at the impact site.…”

Comparing Two Processing Pipelines to Measure Subcortical and Cortical Volumes in Patients with and without Mild Traumatic Brain Injury

“…Three, FreeSurfer can be used to generate unique, cohort‐specific control data that are transparent to the user. The issue of controls is becoming increasingly a topic of interest as unique hardware and demographic features likely affect the quality and the nature of the imaging data and consequently the volumetric output …”

“…Neuroimaging technology has made rapid advances over the past two decades revealing additional information about a number of neurologic processes. In particular, magnetic resonance imaging (MRI) has seen technological improvements in resolution, speed of acquisition, the addition of new sequences, and 3‐dimensional visualization of complex anatomy . Combined, these improvements have changed the way images are used in clinical settings and there are many efforts to establish more standardized evidence‐based uses that will inform clinical understanding of the extent, location, type, progression, and prognosis of an injury or disease process.…”

Volumetric and shape analyses of subcortical structures in United States service members with mild traumatic brain injury

“…One of the primary clinical and research tools employed in examining the effects of TBI on brain structure has been medical imaging, especially quantitative or volumetric magnetic resonance imaging (MRI; [5, 6, 17, 61, 72]). Across the range of TBI severity, these studies have demonstrated a number of consistent findings including global atrophy (i.e., ventricle-to-brain ratio; [5, 65]), white and gray matter atrophy [6, 47, 64], regional vulnerability (temporal and frontal poles [4]) specific subcortical nuclei atrophy (i.e., thalamus, [43]), and cortical thinning [38, 66, 73]).…”