scholarly journals Brain Connectivity Affecting Gait Function after Unilateral Supratentorial Stroke

2021 ◽  
Vol 11 (7) ◽  
pp. 870
Author(s):  
Hyun-Ah Lee ◽  
Dae-Hyun Kim
Keyword(s):  
Diffusion Tensor Imaging ◽  
Corpus Callosum ◽  
Fractional Anisotropy ◽  
Motor Coordination ◽  
Diffusion Tensor ◽  
Brain Connectivity ◽  
Structural Connectivity ◽  
Mean Diffusivity ◽  
Medial Lemniscus ◽  
Gait Function

Gait dysfunction is a leading cause of long-term disability after stroke. The mechanisms underlying recovery of gait function are unknown. We retrospectively evaluated the association between structural connectivity and gait function in 127 patients with unilateral supratentorial stroke (>1 month after stroke). All patients underwent T1-weighted, diffusion tensor imaging and functional ambulation categorization. Voxel-wise linear regression analyses of the images were conducted using fractional anisotropy, mean diffusivity, and mode of anisotropy mapping as dependent variables, while the functional ambulation category was used as an independent variable with age and days after stroke as covariates. The functional ambulation category was positively associated with increased fractional anisotropy in the lesioned cortico-ponto-cerebellar system, corona radiata of the non-lesioned corticospinal tract pathway, bilateral medial lemniscus in the brainstem, and the corpus callosum. The functional ambulation category was also positively associated with increased mode of anisotropy in the lesioned posterior corpus callosum. In conclusion, structural connectivity associated with motor coordination and feedback affects gait function after stroke. Diffusion tensor imaging for evaluating structural connectivity can help to predict gait recovery and target rehabilitation goals after stroke.

Segmental Diffusion Properties of the Corticospinal Tract and Motor Outcome in Hemiparetic Children With Perinatal Stroke

2017 ◽  
Vol 32 (6) ◽  
pp. 550-559 ◽  
Author(s):  
Jacquie Hodge ◽  
Bradley Goodyear ◽  
Helen Carlson ◽  
Xing-Chang Wei ◽  
Adam Kirton
Keyword(s):  
Diffusion Tensor Imaging ◽  
Fractional Anisotropy ◽  
Corticospinal Tract ◽  
Diffusion Tensor ◽  
Model Development ◽  
Structural Connectivity ◽  
Mean Diffusivity ◽  
Radial Diffusivity ◽  
Perinatal Stroke ◽  
Motor Outcomes

Perinatal stroke injures developing motor systems, resulting in hemiparetic cerebral palsy. Diffusion tensor imaging can explore structural connectivity. We used diffusion tensor imaging to assess corticospinal tract diffusion in hemiparetic children with perinatal stroke. Twenty-eight children (6-18 years) with unilateral stroke underwent diffusion tensor imaging. Four corticospinal tract assessments included full tract, partial tract, minitract and region of interest. Diffusion characteristics (fractional anisotropy, mean, axial, and radial diffusivity) were calculated. Ratios (lesioned/nonlesioned) were compared across segments and to validated long-term motor outcomes (Pediatric Stroke Outcome Measure, Assisting Hand Assessment, Melbourne Assessment). Fractional anisotropy and radial diffusivity ratios decreased as tract size decreased, while mean diffusivity showed consistent symmetry. Poor motor outcomes were associated with lower fractional anisotropy in all segments and radial diffusivity correlated with both Assisting Hand Assessment and Melbourne Assessment. Diffusion imaging of segmented corticospinal tracts is feasible in hemiparetic children with perinatal stroke. Correlations with disability support clinical relevance and utility in model development for personalized rehabilitation.

scholarly journals Diffusion Tensor Imaging of the Kidneys: Influence of b-Value and Number of Encoding Directions on Image Quality and Diffusion Tensor Parameters

2013 ◽  
Vol 3 ◽  
pp. 53 ◽  
Author(s):  
Natalie C. Chuck ◽  
Günther Steidle ◽  
Iris Blume ◽  
Michael A. Fischer ◽  
Daniel Nanz ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
Image Quality ◽  
Fractional Anisotropy ◽  
Diffusion Tensor ◽  
Mean Diffusivity ◽  
Renal Medulla ◽  
Whole Body ◽  
Acquisition Time ◽  
Data Sets ◽  
B Values

Objectives: The purpose of this study was to evaluate to which degree investment of acquisition time in more encoding directions leads to better image quality (IQ) and what influence the number of encoding directions and the choice of b-values have on renal diffusion tensor imaging (DTI) parameters. Material and Methods: Eight healthy volunteers (32.3 y ± 5.1 y) consented to an examination in a 1.5T whole-body MR scanner. Coronal DTI data sets of the kidneys were acquired with systematic variation of b-values (50, 150, 300, 500, and 700 s/mm2) and number of diffusion-encoding directions (6, 15, and 32) using a respiratory-triggered echo-planar sequence (TR/TE 1500 ms/67 ms, matrix size 128 × 128). Additionally, two data sets with more than two b-values were acquired (0, 150, and 300 s/mm2 and all six b-values). Parametrical maps were calculated on a pixel-by-pixel basis. Image quality was determined with a reader score. Results: Best IQ was visually assessed for images acquired with 15 and 32 encoding directions, whereas images acquired with six directions had significantly lower IQ ratings. Image quality, fractional anisotropy, and mean diffusivity only varied insignificantly for b-values between 300 and 500 s/mm2. In the renal medulla fractional anisotropy (FA) values between 0.43 and 0.46 and mean diffusivity (MD) values between 1.8-2.1 × 10-3 mm2/s were observed. In the renal cortex, the corresponding ranges were 0.24-0.25 (FA) and 2.2-2.8 × 10-3 mm2/s (MD). Including b-values below 300 s/mm2, notably higher MD values were observed, while FA remained constant. Susceptibility artifacts were more prominent in FA maps than in MD maps. Conclusion: In DTI of the kidneys at 1.5T, the best compromise between acquisition time and resulting image quality seems the application of 15 encoding directions with b-values between 300 and 500 s/mm2. Including lower b-values allows for assessment of fast diffusing spin components.

scholarly journals Heterogeneity of Fractional Anisotropy and Mean Diffusivity Measurements by In Vivo Diffusion Tensor Imaging in Normal Human Hearts

PLoS ONE ◽  
2015 ◽  
Vol 10 (7) ◽  
pp. e0132360 ◽  
Author(s):  
Laura-Ann McGill ◽  
Andrew D. Scott ◽  
Pedro F. Ferreira ◽  
Sonia Nielles-Vallespin ◽  
Tevfik Ismail ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
Fractional Anisotropy ◽  
Diffusion Tensor ◽  
Mean Diffusivity ◽  
Diffusivity Measurements ◽  
Normal Human

scholarly journals A diffusion tensor imaging study of structural dysconnectivity in never-medicated, first-episode schizophrenia

2007 ◽  
Vol 38 (6) ◽  
pp. 877-885 ◽  
Author(s):  
V. Cheung ◽  
C. Cheung ◽  
G. M. McAlonan ◽  
Y. Deng ◽  
J. G. Wong ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Corpus Callosum ◽  
Diffusion Tensor ◽  
Structural Connectivity ◽  
First Episode ◽  
Cerebral Peduncle ◽  
Healthy Controls ◽  
Subcortical Region ◽  
First Episode Schizophrenia

BackgroundDiffusion tensor imaging (DTI) can be used to investigate cerebral structural connectivity in never-medicated individuals with first-episode schizophrenia.MethodSubjects with first-episode schizophrenia according to DSM-IV-R who had never been exposed to antipsychotic medication (n=25) and healthy controls (n=26) were recruited. Groups were matched for age, gender, best parental socio-economic status and ethnicity. All subjects underwent DTI and structural magnetic resonance imaging (MRI) scans. Voxel-based analysis was performed to investigate brain regions where fractional anisotropy (FA) values differed significantly between groups. A confirmatory region-of-interest (ROI) analysis of FA scores was performed in which regions were placed blind to group membership.ResultsIn patients, FA values significantly lower than those in healthy controls were located in the left fronto-occipital fasciculus, left inferior longitudinal fasciculus, white matter adjacent to right precuneus, splenium of corpus callosum, right posterior limb of internal capsule, white matter adjacent to right substantia nigra, and left cerebral peduncle. ROI analysis of the corpus callosum confirmed that the patient group had significantly lower mean FA values than the controls in the splenium but not in the genu. The intra-class correlation coefficient (ICC) for independent ROI measurements was 0.90 (genu) and 0.90 (splenium). There were no regions where FA values were significantly higher in the patients than in the healthy controls.ConclusionsWidespread structural dysconnectivity, including the subcortical region, is already present in neuroleptic-naive patients in their first episode of illness.

scholarly journals Perivascular space fluid contributes to diffusion tensor imaging changes in white matter

2018 ◽  
Author(s):  
Farshid Sepehrband ◽  
Ryan P Cabeen ◽  
Jeiran Choupan ◽  
Giuseppe Barisano ◽  
Meng Law ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Fractional Anisotropy ◽  
Diffusion Mri ◽  
Diffusion Tensor ◽  
Diffusion Imaging ◽  
Mean Diffusivity ◽  
Brain Parenchyma ◽  
Perivascular Space ◽  
List Type

AbstractDiffusion tensor imaging (DTI) has been extensively used to map changes in brain tissue related to neurological disorders. Among the most widespread DTI findings are increased mean diffusivity and decreased fractional anisotropy of white matter tissue in neurodegenerative diseases. Here we utilize multi-shell diffusion imaging to separate diffusion signal of the brain parenchyma from fluid within the white matter. We show that unincorporated anisotropic water in perivascular space (PVS) significantly, and systematically, biases DTI measures, casting new light on the biological validity of many previously reported findings. Despite the challenge this poses for interpreting these past findings, our results suggest that multi-shell diffusion MRI provides a new opportunity for incorporating the PVS contribution, ultimately strengthening the clinical and scientific value of diffusion MRI.HighlightsPerivascular space (PVS) fluid significantly contributes to diffusion tensor imaging metricsIncreased PVS fluid results in increased mean diffusivity and decreased fractional anisotropyPVS contribution to diffusion signal is overlooked and demands further investigation

scholarly journals Reduction of bias in the evaluation of fractional anisotropy and mean diffusivity in magnetic resonance diffusion tensor imaging using region-of-interest methodology

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Youngseob Seo ◽  
Nancy K. Rollins ◽  
Zhiyue J. Wang
Keyword(s):  
Diffusion Tensor Imaging ◽  
Fractional Anisotropy ◽  
Diffusion Tensor ◽  
Signal To Noise Ratio ◽  
Mean Diffusivity ◽  
Region Of Interest ◽  
Superior Temporal Gyrus ◽  
Brain Structures ◽  
Equivalence Test ◽  
Mr Diffusion

Abstract Accurate quantification of fractional anisotropy (FA) and mean diffusivity (MD) in MR diffusion tensor imaging (DTI) requires adequate signal-to-noise ratio (SNR) especially in low FA areas of the brain, which necessitates clinically impractical long image acquisition times. We explored a SNR enhancement strategy using region-of-interest (ROI)-based diffusion tensor for quantification. DTI scans from a healthy male were acquired 15 times and combined into sets with different number of signal averages (NSA = 1–4, 15) at one 1.5-T Philips and three 3-T (Philips, Siemens and GE) scanners. Equivalence test was performed to determine NSA thresholds for bias-free FA and MD quantifications by comparison with reference values derived from images with NSA = 15. We examined brain areas with low FA values including caudate nucleus, globus pallidus, putamen, superior temporal gyrus, and substructures within thalamus (lateral dorsal, ventral anterior and posterior nuclei), where bias-free FA is difficult to obtain using a conventional approach. Our results showed that bias-free FA can be obtained with NSA = 2 or 3 in some cases using ROI-based analysis. ROI-based analysis allows reliable FA and MD quantifications in various brain structures previously difficult to study with clinically feasible data acquisition schemes.

Sign in / Sign up

Export Citation Format

Share Document