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Analysis of brain tracks using advanced diffusion methods
Daňková, Martina ; Gajdoš, Martin (referee) ; Vojtíšek, Lubomír (advisor)
The aim of this bachelor’s thesis is to analyze brain pathways using advanced diffusion magnetic resonance methods. The literature review describes the principles of diffusion-weighted imaging, methods of data collection and processing, and available software for analyzing diffusion-weighted data. The practical part of the thesis focuses on designing a functional solution for the analysis of diffusion-weighted data, which is tested on a reduced dataset containing healthy controls and patients with multiple sclerosis. A complete preprocessing, tractographic analysis, and connectome construction are performed on a reduced sample of healthy and ill patients. Additionally, an analysis of the differences between the connectomes of the healthy and the ill is conducted.
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Multi-tensor model based tractography of axonal bundles
Piskořová, Zuzana ; Jiřík, Radovan (referee) ; Labounek, René (advisor)
Cílem semestrální práce je návrh trasovacího algoritmu, který zohledňuje mikrostrukturní vlastnosti nervové tkáně. K této problematice je sepsána rešerše obsahující úvod do problematiky. Je zde popsán jev difuze, princip difuzně váženého MRI a odhad profilu anizotropní difuze. K podrobnější analýze byl vybrán algoritmus COMMIT, u kterého byla navržena alternativní optimalizační metoda.
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Tracking of axonal bundles in diffusion MRI brain images
Piskořová, Zuzana ; Vojtíšek, Lubomír (referee) ; Labounek, René (advisor)
The aim of this thesis is to design tracking algorithm which will be able to track white matter bundles in diffusion MRI data, this problem is called tractography. Tractography is feasible because specific profile of diffusion appears in white matter. The introduction to the topic includes summary of methods for estimation of diffusion profile and basic tracking algorithms. In this work diffusion tensor model (DTI) was used for estimation of diffusion profile. Based on the DTI, vector field characterizing direction of diffusion for every voxel was created. Combining vector field with seedpoint, we achieved task solvable by Euler or Runge-Kutta method. Termination criteria were established for maximum curvature of trajectory and minimum value of fractional anisotropy (FA). Algorithm was tested on mathematical and tractographical phantom before it was used on real biological data. The results of tracking on phantoms proved the funcionality of the algorithm. Expected error appeared in areas of crossing fibers, it is related to DTI model limitations. To solve problematic fibers characterized by seedpoint near the border of the fiber, FA-weighted trilinear interpolation was designed. Implementation of this algorithm, however, did not cause better results. The results of tracking on the real data were controversial. Tracking was performed on 5 healthy subjects and 4 anatomicaly specific tracts. The results were compared with tractographic atlas.
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Altered morphology of white and grey matter in patients with Alzheimer disease and Schizophrenia on MRI
Lahutsina, Anastasiya ; Zach, Petr (advisor) ; Horáček, Jiří (referee) ; Němcová, Veronika (referee)
Cortical folding of the anterior cingulate cortex (ACC), particularly the cingulate (CS) and the paracingulate (PCS) sulci, represents a neurodevelopmental marker. Deviations in in utero development in schizophrenia can be traced using CS and PCS morphometry. In the present study, we measured the length of CS, PCS, and their segments on T1 MRI scans in 93 patients with first episode schizophrenia and 42 healthy controls. Besides the length, the frequency and the left-right asymmetry of CS/PCS were compared in patients and controls. Distribution of the CS and PCS morphotypes in patients was different from controls. Parcellated sulcal pattern CS3a in the left hemisphere was longer in patients (53.8 ± 25.7 mm vs. 32.7 ± 19.4 mm in controls, p < 0.05), while in CS3c it was reversed-longer in controls (52.5 ± 22.5 mm as opposed to 36.2 ± 12.9 mm, n.s. in patients). Non parcellated PCS in the right hemisphere were longer in patients compared to controls (19.4 ± 10.2 mm vs. 12.1 ± 12.4 mm, p < 0.001). Therefore, concurrent presence of PCS1 and CS1 in the left hemisphere and to some extent in the right hemisphere may be suggestive of a higher probability of schizophrenia. Measurement of an hippocampal area or volume is useful in clinical practice as a supportive aid for diagnosis of Alzheimer's disease....
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Multi-tensor model based tractography of axonal bundles
Piskořová, Zuzana ; Jiřík, Radovan (referee) ; Labounek, René (advisor)
Cílem semestrální práce je návrh trasovacího algoritmu, který zohledňuje mikrostrukturní vlastnosti nervové tkáně. K této problematice je sepsána rešerše obsahující úvod do problematiky. Je zde popsán jev difuze, princip difuzně váženého MRI a odhad profilu anizotropní difuze. K podrobnější analýze byl vybrán algoritmus COMMIT, u kterého byla navržena alternativní optimalizační metoda.
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Tracking of axonal bundles in diffusion MRI brain images
Piskořová, Zuzana ; Vojtíšek, Lubomír (referee) ; Labounek, René (advisor)
The aim of this thesis is to design tracking algorithm which will be able to track white matter bundles in diffusion MRI data, this problem is called tractography. Tractography is feasible because specific profile of diffusion appears in white matter. The introduction to the topic includes summary of methods for estimation of diffusion profile and basic tracking algorithms. In this work diffusion tensor model (DTI) was used for estimation of diffusion profile. Based on the DTI, vector field characterizing direction of diffusion for every voxel was created. Combining vector field with seedpoint, we achieved task solvable by Euler or Runge-Kutta method. Termination criteria were established for maximum curvature of trajectory and minimum value of fractional anisotropy (FA). Algorithm was tested on mathematical and tractographical phantom before it was used on real biological data. The results of tracking on phantoms proved the funcionality of the algorithm. Expected error appeared in areas of crossing fibers, it is related to DTI model limitations. To solve problematic fibers characterized by seedpoint near the border of the fiber, FA-weighted trilinear interpolation was designed. Implementation of this algorithm, however, did not cause better results. The results of tracking on the real data were controversial. Tracking was performed on 5 healthy subjects and 4 anatomicaly specific tracts. The results were compared with tractographic atlas.
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