Longitudinal changes in patients with traumatic brain injury assessed with diffusion-tensor and volumetric imaging

Abstract

Traumatic brain injury (TBI) is associated with brain volume loss, but there is little information on the regional gray matter (GM) and white matter (WM) changes that contribute to overall loss. Since axonal injury is a common occurrence in TBI, imaging methods that are sensitive to WM damage such as diffusion-tensor imaging (DTI) may be useful for characterizing microstructural brain injury contributing to regional WM loss in TBI. High-resolution T1-weighted imaging and DTI were used to evaluate regional changes in TBI patients compared to matched controls. Patients received neuropsychological testing and were imaged approximately 2 months and 12.7 months post-injury. Paradoxically, neuropsychological function improved from Visit 1 to Visit 2, while voxel-based analyses of fractional anisotropy (FA), and mean diffusivity (MD) from the DTI images, and voxel-based analyses of the GM and WM probability maps from the T1-weighted images, mainly revealed significantly greater deleterious GM and WM change over time in patients compared to controls. Cross-sectional comparisons of the DTI measures indicated that patients have decreased FA and increased MD compared to controls over large regions of the brain. TBI affected virtually all of the major fiber bundles in the brain including the corpus callosum, cingulum, the superior and inferior longitudinal fascicules, the uncinate fasciculus, and brain stem fiber tracts. The results indicate that both GM and WM degeneration are significant contributors to brain volume loss in the months following brain injury, and also suggest that DTI measures may be more useful than high-resolution anatomical images in assessment of group differences.

Emerging Imaging Tools for Use with Traumatic Brain Injury Research

“…First, volumetric changes can evolve over an extended time (Sidaros et al, 2009;Trivedi et al, 2007;Wu et al, 2010a) and may be evident later than changes seen on other advanced imaging techniques such as DTI (Bendlin et al, 2008;Groen et al, 2010;Hutchinson et al, 2010;Wu et al, 2010a). It should be kept in mind that the relation between tissue integrity, as measured by volumetry, and outcome may be dynamic and complex, particularly in the earlier phases of recovery, as trajectories of rapid cognitive recovery and incomplete degenerative tissue change may be progressing in opposing directions and to differing degrees.…”

“…More importantly, changes in DTIderived measures have shown correlation with injury severity (Arfanakis et al, 2002;Benson et al, 2007;Wilde et al, 2010;Yuan et al, 2007), functional outcome (Huisman et al, 2004;Levin et al, 2008;Salmond et al, 2006;Wozniak et al, 2007), neurologic functioning (Caeyenberghs et al, 2010a,b), and cognitive ability (Bigler et al, 2010b;Ewing-Cobbs et al, 2008;Kraus et al, 2007;Kumar et al, 2009;Levin et al, 2008;McCauley et al, 2011;Niogi et al, 2008;Salmond et al, 2006;Warner et al, 2010a;Wilde et al, 2010). Longitudinal studies have also indicated that DTI might serve as a tool for revealing changes in the neural tissue during recovery from TBI (Bendlin et al, 2008;Sidaros et al, 2008;Wu et al, 2010a). DTI remains a promising tool in TBI research and clinical practice for 1) assisting in clinical diagnosis (particularly in mild TBI) (Bazarian et al, 2007;Mayer et al, 2010;Miles et al, 2008;Wilde et al, 2008) and prognosis (Newcombe et al, 2007;Perlbarg et al, 2009); 2) understanding the nature and time course of degenerative brain changes in vivo; 3) uncovering potential evidence for neuroplastic changes (e.g., reorganization or recovery); and 4) evaluating therapeutic interventions and rehabilitation.…”

Strategy‐based reasoning training modulates cortical thickness and resting‐state functional connectivity in adults with chronic traumatic brain injury

“…MRI‐based morphometry has revealed altered cortical thickness and volume within individuals who have sustained a TBI (Bendlin et al., 2008; Gale, Baxter, Roundy, & Johnson, 2005; Kim et al., 2008; Sidaros et al., 2009; Spitz et al., 2013; Tate et al., 2014; Turken et al., 2009; Warner et al., 2010; Zhou et al., 2013). These altered cortical morphometric properties are frequently associated with functional deficits (Gale et al., 2005; Palacios et al., 2013; Sidaros et al., 2009; Spitz et al., 2013; Warner et al., 2010; Zhou et al., 2013), and correspondences between MRI‐based and histological morphometric data of TBI individuals have been reported (Maxwell, MacKinnon, Stewart, & Graham, 2009).…”

Diffusion-Derived Magnetic Resonance Imaging Measures of Longitudinal Microstructural Remodeling Induced by Marrow Stromal Cell Therapy after Traumatic Brain Injury

“…These structural alterations within the injured brain can be revealed by magnetic resonance imaging (MRI), especially diffusion measurements. [16][17][18][19][20][21] By exploiting the anisotropic properties of water diffusion in white matter (WM), diffusion imaging technology provides new insights into the microstructural organization of the central nervous system. As a noninvasive tool capable of characterizing the major diffusion direction of fiber tracts, diffusion-tensor imaging (DTI) 22 maps the orientational architecture of neural tissue in vivo.…”