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DTI of Neurodegenerative Disorders
Published in Andrei I. Holodny, Functional Neuroimaging, 2019
Sumei Wang, John H. Woo, Elias R. Melhem
DTI can evaluate the brain tissue damage in FTD. Larsson et al. (67) first applied DTI to the formalin-fixed brain of an FTD patient. Decreased diffusion anisotropy was observed in the bilateral frontal WM. Yoshiura et al. (68) demonstrated elevated ADC in the frontal and temporal WM using diffusion-weighted imaging (DWI). In a recent study, Borroni et al. (69), based on major clinical presentation, classified FTD into two types: frontal variant and temporal variant. The frontal variant group showed a selective WM reduction in the superior longitudinal fasciculus, while the temporal variant group demonstrated WM reductions in the inferior longitudinal fasciculus.
Non-Synonyms (Similar-Sounding)
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
Inferior longitudinal fasciculus (B&K, p. 243): A bundle of long cerebral association fibers connecting occipital and temporal cortex. Some authors consider this fasciculus to also contain some of the optic radiations (e.g., Ranson and Clark, 1953, p. 301).
Mapping the Injured Brain
Published in Yu Chen, Babak Kateb, Neurophotonics and Brain Mapping, 2017
Chandler Sours, Jiachen Zhuo, Rao P. Gullapalli
Recent studies using DTI tend to focus primarily on alterations in the WM microstructure associated with DAI due to the great sensitivity of FA and axial/radial diffusivity in detecting axonal injury. Region of interest (ROI) analysis based on either anatomical regions or tractography-based tract regions indicate that commonly damaged regions following TBI include the corpus callosum (Bazarian et al., 2007; Kumar et al., 2009; Mayer et al., 2010; Warner et al., 2010a), internal capsule (Arfanakis et al., 2002; Bazarian et al., 2007), and cingulum bundles (Mac Donald et al., 2011). More recently, whole-brain analysis, such as tract-based spatial statistics (TBSS) (Smith et al., 2006), revealed more widely spread WM abnormalities extending to the superior and inferior longitudinal fasciculus, corona radiate, frontal and temporal lobes, etc. (Messe et al., 2011; Yuh et al., 2013), which is consistent with the diffuse nature of the injury. Alterations in DTI parameters following TBI, most strongly FA, have been widely demonstrated, correlating with injury severity (Benson et al., 2007) and/or functional outcomes after TBI, including neuropsychological scores (Kraus et al., 2007; Niogi et al., 2008), GOS (Sidaros et al., 2008), and postconcussive symptoms (Wilde et al., 2008). More importantly, acute DTI abnormalities have shown prognostic values in predicting outcomes in severe TBI (Betz et al., 2012; Shanmuganathan et al., 2004). Even in mTBI, FA reduction in at least one region in the brain was shown to be the most robust predictor for 6-month outcome, over conventional MRI and/or any other clinical, demographic/socioeconomic characteristics (Yuh et al., 2013). Figure 14.5 demonstrates diffuse acute FA reduction in mTBI patients (n = 14) who had eventual worsening symptoms at 6 months compared to a control group (n = 30), while no changes in FA were noted in a group of patients (n = 11) who had eventual improvement of symptom severity.
Diffusion tensor imaging of white matter degeneration in early stage of Alzheimer's disease: a review
Published in International Journal of Neuroscience, 2020
Viviana Lo Buono, Rosanna Palmeri, Francesco Corallo, Cettina Allone, Deborah Pria, Placido Bramanti, Silvia Marino
Liu et al. [26] analyzed microstructural abnormalities between two subtypes of MCI, amnestic MCI single domain (MCI-s) and MCI multiple domain (MCI-m) compared to 23 HC. Authors found that MCI groups showed a reduced FA in right superior longitudinal fasciculus (SLF), than HC; in addition, aMCI-s showed significantly decreased FA values in left SLF, left Uncinate Fasciculus and left inferior longitudinal fasciculus, more than aMCI-m group. So, although FA abnormalities are common in both aMCI groups, these findings suggested that the two types of aMCI have different DTI pathways. Authors hypothesized that DTI, in comparison with traditional imaging and neuropsychological evaluation, could represent a sensitive technique for differential diagnosis of aMCI-s and aMCI-m. To investigate cross-sectional and longitudinal change in the integrity of WM microstructure in AD patients, Elahi et al. [27] used DTI metrics (FA and MD) as surrogate biomarkers of disease progression, identifying regions of WM where the rate of change was significantly faster in AD compared with HC. The AD group showed statistically significant baseline and longitudinal WM degeneration with predominant involvement of posterior tracts.
Longitudinal examination of the relationship between changes in white matter organization and cognitive outcome in chronic TBI
Published in Brain Injury, 2019
Kathy S. Chiou, Tony Jiang, Nancy Chiaravalloti, Matthew J. Hoptman, John DeLuca, Helen Genova
The results of the current study provide evidence of dynamic recovery occurring years after initial injury. Results revealed an increase in FA of the right inferior longitudinal fasciculus over a span of 3 years in a sample of adults with moderate and severe TBI who were in the chronic stages of recovery (approximately 7 years since injury). Furthermore, results showed that improvements on a set-shifting task were correlated with increased FA in the left forceps minor and cingulum, as well as the right superior longitudinal fasciculus, forceps major, inferior fronto-occipital fasciculus, uncinate, and inferior longitudinal fasciculus. These preliminary findings suggest that changes in white matter organization and corresponding functional recovery extend beyond the immediate years following injury. This potentially expanded trajectory of recovery and possible plasticity have important implications for the investment in rehabilitation efforts in chronic stages. Future studies are needed to determine mediating and/or moderating factors that influence these observed changes.
An investigation of white matter integrity and attention deficits following traumatic brain injury
Published in Brain Injury, 2018
Jacqueline Anne Owens, Gershon Spitz, Jennie Louise Ponsford, Alicia Rhian Dymowski, Catherine Willmott
TBSS studies have identified a number of white matter tracts to be associated with attentional deficits post-TBI. Reduced white matter integrity in the superior longitudinal fasciculus, corpus callosum and cingulum has been found to be implicated in switching of attention (16), as well as speed of initiation and response inhibition (9). Additionally, the left inferior longitudinal fasciculus (9), right corticospinal tract and left frontal white matter (16) were also found to be associated with attentional measures. Interestingly, Kinnunen and colleagues (16) found no significant association between performance on a choice reaction task, a measure of processing speed and DTI metrics. Contrary to this, using the Symbol Digit Modalities Test (SDMT), Spitz and colleagues (9) found information processing speed to be associated with an extensive network of tracts throughout the brain, including the left and right inferior longitudinal fasciculus, left and right superior longitudinal fasciculus, corpus callosum and cingulate bundle. Using TBSS, Palacios and colleagues (10) investigated working memory using both TBSS and ROI analysis. Their TBSS analysis identified a positive correlation between the ability to discriminate between correct and incorrect responses on the 2-back and whole-brain FA. These studies have provided preliminary evidence for involvement of a number of white matter pathways in attentional deficits post-TBI, particularly long association tracts.