scholarly journals Segmentation of Brain Structures by Watershed Transform on Tensorial Morphological Gradient of Diffusion Tensor Imaging

Author(s):  
Leticia Rittner ◽  
Simone Appenzeller ◽  
Roberto Lotufo
2011 ◽  
Vol 26 (S2) ◽  
pp. 960-960
Author(s):  
J.L. Villegas Martínez ◽  
J.A. Blanco Garrote ◽  
F. Uribe Ladrón de Cegama ◽  
B. Arribas Simón ◽  
G. Cabús Piñol

IntroductionDiffusion tensor imaging (DTI) is a magnetic resonance imaging technique that have increasingly being used for the non-invasive evaluation of brain white matter (WM) abnormalities. Several studies suggest that the normal integration of cerebral function may be compromised in schizophrenia. Abnormalities in WM tracts may be directly relevant for the neuropathology of schizophrenia.ObjetivesThe purpose of this review was to discuss recent DTI findings in schizophrenia and a methodologic analysis.MethodsThe literature search was performed with the search engine PubMed of the U.S. National Library of Medicine. Search strategy used was based on the Cochrane review technique, limited to the period between 1998 (first report on DTI and schizophrenia) and May 2010. And limited to ‘Title/Abstract’. The reference lists of these studies were used to identify additional studies.ResultsThere is a striking amount of heterogeneity in findings, probably by methodologic problems. Brain regions such as the cingulate bundle, corpus callosum, and regions within frontal and temporal WM have a proportionally larger number of positive findings across the studies. In addition, WM tracts as The superior longitudinal fasciculus, fronto-occipital longitudinal fasciculi, uncinate fasciculi, frontal longitudinal fasciculus and the arcuate fasciculus have also positive findings in patients with schizophrenia. Other brain structures as the cerebellar peduncles, the fornix, the hippocampus and parahippocampal gyrus, the thalamic and optic radiations have been evaluated and shown positive findings. However, these findings are not present in all studies. DTI abnormalities in first-episode patients are less robust than in chronic patients.ConclusionsRecent DTI findings further support the hypothesis of structural dysconnectivity in schizophrenia.


Trauma ◽  
2019 ◽  
Vol 22 (3) ◽  
pp. 182-192
Author(s):  
Andrew Post ◽  
Eyesha Hashim ◽  
Windsor Kwan-Chun Ting ◽  
T. Blaine Hoshizaki ◽  
Michael D. Gilchrist ◽  
...  

Background Concussion is an injury that occurs in non-sporting and sporting environments. To determine improved clinical methods for identifying this injury, it is important to develop and understand how the impact event results in quantifiable differences in brain functioning—functioning that has been quantified in the past using saccadic measures. The purpose of this research was to examine the relationships between oculomotor deficits, specifically antisaccade responses, and the biomechanics of impact for a concussion. Methods Participants underwent a diffusion tensor imaging protocol as well as saccadic testing to determine differences in brain functioning in comparison to controls. The injury event was then reconstructed in laboratory using physical and finite element models to determine the biomechanics of the impact and brain tissue strain. Relationships between the biomechanical variables and antisaccade responses were then examined. Results The diffusion tensor imaging analyses found that there was a decrease in radial diffusivity and axial diffusivity found in the cerebral peduncle (p < 0.05) and cingulum hippocampus (p < 0.05), respectively. There was an increase in the axial diffusivity for the corona radiata (p < 0.05). The saccadic testing found an increase in mean latency for the concussed group (p < 0.05). The results indicated no significant relationship between mean latency, duration, amplitude and peak velocity antisaccade measures and the biomechanical variables. This may have been influenced not only by a lack of sensitivity in biomechanical variable to antisaccade responses, but also to these responses being affected by factors other than injury such as attentiveness and wakefulness. Conclusion While the sample of this research was small, this research suggests that to improve the understanding of the relationship between impact biomechanics and concussion, methods that can quantify the damage to brain structures through imaging, such as diffusion tensor imaging, may be more appropriate.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Youngseob Seo ◽  
Nancy K. Rollins ◽  
Zhiyue J. Wang

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.


2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Thomas J. Whitford ◽  
Marek Kubicki ◽  
Martha E. Shenton

A fundamental tenet of the “disconnectivity” theories of schizophrenia is that the disorder is ultimately caused by abnormal communication between spatially disparate brain structures. Given that the white matter fasciculi represent the primary infrastructure for long distance communication in the brain, abnormalities in these fiber bundles have been implicated in the etiology of schizophrenia. Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique that enables the visualization of white matter macrostructurein vivo, and which has provided unprecedented insight into the existence and nature of white matter abnormalities in schizophrenia. The paper begins with an overview of DTI and more commonly used diffusion metrics and moves on to a brief review of the schizophrenia literature. The functional implications of white matter abnormalities are considered, particularly with respect to myelin's role in modulating the transmission velocity of neural discharges. The paper concludes with a speculative hypothesis about the relationship between gray and white matter abnormalities associated with schizophrenia.


2019 ◽  
Vol 10 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Viktor S. Lvov ◽  
Aleksandr V. Pozdnyakov ◽  
Dmitry O. Ivanov ◽  
Alexey I. Tashilkin ◽  
Leonid M. Makarov ◽  
...  

The aim of the study was to determine the capabilities of magnetic resonance morphometry and diffusion tensor imaging in the diagnosis of bilateral spastic forms of cerebral palsy in children. The main groups were 33 children aged from 1 year to 4 years 5 months. with bilateral spastic forms of cerebral palsy, the comparison group – 11 children who did not have movement disorders. The patients underwent magnetic resonance morphometry, diffusion tensor imaging. A comparison was made between the volumes of brain structures and diffusion values between groups. Significant differences (p < 0,05) were found in the volumes of the right lateral, 3rd ventricles, white matter, thalamuses, globus pallidus, putamen, hippocampus. Significant differences (p < 0,05) in diffusion values in the thalamuses and in the posterior limb of internal capsules were also identified. The correlation of the identified changes with the clinic of the disease was demonstrated. The obtained data demonstrate wide possibilities and high diagnostic value in the detection of bilateral spastic forms of cerebral palsy in children.


2010 ◽  
Vol 31 (3) ◽  
pp. 482-493 ◽  
Author(s):  
Adolf Pfefferbaum ◽  
Elfar Adalsteinsson ◽  
Torsten Rohlfing ◽  
Edith V. Sullivan

NeuroImage ◽  
2021 ◽  
pp. 118863
Author(s):  
Bruce Luber ◽  
Simon W. Davis ◽  
Zhi-De Deng ◽  
David Murphy ◽  
Andrew Martella ◽  
...  

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