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The use of functional magnetic resonance imaging and MR tractography for neuropsychiatirc studies of cognitive functions
Ibrahim, Ibrahim ; Hájek, Milan (advisor) ; Vymazal, Josef (referee) ; Žižka, Jan (referee)
5. Summary Although conventiona! MR imaging techniques play a crucia! role in the examination of the centra!nervous system (CNS), these techniques can not give any information about functiona! properties of the brain tissue. Besides conventional MRl techniques, however, there are some MR methods enabling evaluation of these functiona! properties. These methods include functiona! magnetic resonance imaging (!MRl), diffusion-weigbted imaging (DWI) or diffusion tensor imaging (DTI), and voxel based morphometry (VBM). fMRI is a method monitoring the activity of the individua! parts of the brain duriog specific tasks and thus c1arifying their functions. fMRI has become the method of choice especia!ly in neurosurgica! procedures plarming, when it is necessary to know the relative location of the pathological lesion and to localize functiona!ly important areas of the cerebra! cortex, and thereby to reduce the risk of damage associated with the neurosurgical operations. DWI and DT[ are very important methods that may be used to assess the severity of cerebra! ischemia and the integrity ofwhite matter tracts based on diffusion properties ofthe brain tissue. Voxel·based morphometry (VBM) is an objective method and fuHy automated whole brain structura! ana! ysis. Neuropathological changes in the brain tissue of...
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Application of Diffusion Tensor Imaging to Brain Gray and White Marker
Rulseh, Aaron Michael ; Vymazal, Josef (advisor) ; Hluštík, Petr (referee) ; Hájek, Milan (referee)
Application of Diffusion Tensor Imaging to Brain Gray and White Ma er A In the present work we explore the gray and white ma er applicability of diffusion tensor imaging (DTI). To evaluate effect of ferritin-bound iron on gray ma er contrast in DTI, we created an in vitro model consisting of agarose gel phantoms doped with ferritin, and validated our results in vivo on healthy volunteer subjects - years of age in the basal ganglia. We further explored the application of DTI to amyotrophic lateral sclerosis (ALS) and multiple system atrophy (MSA); neurodegenerative diseases with gray and white ma er pathophysiological components. In the ALS study, patients and age- and sex-matched controls were recruited, while the MSA study included probable MSA subjects ( MSA-P, MSA-C) and age- and sex-matched controls. We found that ferritin-bound iron may make a signi cant contribution to DTI scalars in gray ma er regions of the brain, mediated by eigenvalue repulsion. is has important implications for DTI studies targeting gray ma er regions, especially in adolescence and in diseases associated with altered brain-iron load. In ALS, we found altered diffusion in the corona radiata and callosal body, and changes in R in the caudate nucleus and frontal white ma er. In MSA, we observed widespread white ma er changes associated...
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Magnetic resonance volumetric techniques in monitoring disease activity in patients with multiple sclerosis
Andělová, Michaela ; Horáková, Dana (advisor) ; Vymazal, Josef (referee) ; Hluštík, Petr (referee)
Clinical course of multiple sclerosis (MS) is heterogenous and white matter lesion count and volume on brain magnetic resonance imaging (MRI) correlate with clinical course only partially. Therefore, there is an urgent need for more reliable prognostic biomarkers. This work explored three imaging markers - spinal cord (SC) imaging (specifically SC volume measurement and assessment of focal and diffuse SC changes), atlas-based model of "disconnectome" (i.e. disruption of brain connectivity due to white matter lesions) and periventricular white matter gradient assessed with T1 relaxometry. For the SC projects, we assessed MRI from 2044 MS patients with a semi-automatic method for SC volume measurement. We confirmed (i) a relationship between diffuse SC changes, SC volume and disability; (ii) a novel finding was that in patients with EDSS ≤ 4.0, diffuse changes contributed to higher disability more than SC volume; (iii) SC volume explains the paradox in patients with dissociation between brain white matter lesion load and disability; (iv) SC focal and/or diffuse changes are present in 75% patients with early MS, of which 43% have diffuse changes that are related to brainstem lesions. In the disconnectome project, we evaluated the disruption of connectivity caused by white mater lesions in 745 patients...
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The therapeutic benefit of the repetetive transcranial magnetic stimulation on the specific symptoms of schizophrenia
Novák, Tomáš ; Horáček, Jiří (advisor) ; Vymazal, Josef (referee) ; Rektorová, Irena (referee)
The therapeutic benefit of the repetetive transcranial magnetic stimulation on the specific symptoms of schizophrenia Tomas NOVAK Prague Psychiatric Center Summary Transcranial magnetic stimulation is the modern non-invasive method based on the principle of electromagnetic induction. The TMS is widely used in research, diagnostics and treatment of neuropsychiatric disorders. Previous studies imply that repetetive TMS (rTMS) might be useful also in the treatment of some specific symptoms of schizophrenia. The thesis consists of three studies focused on the evaluation of the therapeutic effect of rTMS on specific symptoms of schizophrenia, particularly on negative symptoms and auditory hallucinations. Study 1. The double-blind sham-controlled study of high-frequency rTMS (20Hz) for negative symptoms in schizophrenia The high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) over the prefrontal cortex is a promising method for the treatment of negative symptoms of schizophrenia. Using double-blind, sham- controlled, parallel design, we evaluated the effect of HF-rTMS over the left dorsolateral prefrontal cortex (DLPFC) on negative symptoms in patients with schizophrenia. Sixteen schizophrenia patients with predominantly negative symptoms on stable antipsychotic medication were treated with 20Hz...
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Complex Preoperative Brain Tumor Imaging
Tupý, Radek ; Ferda, Jiří (advisor) ; Vymazal, Josef (referee) ; Tüdös, Zbyněk (referee)
Title Complex preoperative brain tumor imaging Abstract The differentiation of glioblastoma, metastases and brain lymphoma using modern diagnostic imaging methods has a major impact on the strategy of further diagnostic examinations and treatment. In a group of 67 patients with glioblastoma and 31 with cerebral metastasis, the ability to differentiate them according to the evaluation of perfusion parameters changes in peritumoral white matter by T1 dynamic post-contrast magnetic resonance imaging was verified, with the positive predictive value in glioblastoma detection up to 91%. In a group of 36 brain lymphoma patients the importance of imaging submodalities and contribution of a complex magnetic resonance imaging protocol to detect lymphoma up to 80% were evaluated. Key words brain, glioblastoma, lymphoma, magnetic resonance imaging, neoplasm metastasis
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Somatomotor and somatosensory modulation of pain in the EEG and fMR image
Vrána, Jiří ; Stančák, Andrej (advisor) ; Vymazal, Josef (referee) ; Jech, Robert (referee) ; Hájek, Milan (referee)
Pain processing is modulated at different levels of the central nervous system by concurrent sensory and motor processes. From previous studies with innocuous somatosensory evoked potentials we know of the phenomenon of gating by movement. The classical explanation [Melzack R, Wall PD. Pain mechanisms: a new theory. Science 1965;150(699):971-979.] of the mechanism of gating in the posterior horn of spinal cord is complemented by other, lesser understood data, suggesting supraspinal mechanisms. A similar lack of understanding of the cortical mechanisms is seen in pain modulating methods using concurrent electrical nerve stimulation. This work is intended to further our understanding of the cortical mechanisms of pain modulation in the specific cases of (a) isometric muscle contraction of the right or left hand during painful electrical intraepidermal stimulation of the right index finger and (b) during observation of the acute effects of concurrent innocuous median nerve stimulation on painful tonic thermal stimulation of the thenar eminence.
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Pathophysiology and clinical aspects of eye movements in basal ganglia disorders.
Hanuška, Jaromír ; Růžička, Evžen (advisor) ; Vymazal, Josef (referee) ; Jeřábek, Jaroslav (referee)
This dissertation is a collection of a total of seven publications that deal with eye movement disorders in patients with basal ganglia disorders. We obtained normative data for videooculography in healthy individuals. We have described the eye movement evolution during a human life such as the increase of latency, movements become hypometric and antisaccadic error rate increases. We have shown that sex and education do not affect the eye movements. Our study highlighted the asymmetry in the eye movement performance. As the first, we studied the vergence in patients with Parkinson's disease (PN) using videooculography (VOG). We devised and defined a paradigm for this examination and saw that in patients with PN there is a prolonged latency and hypometry of divergence. In patients with ephedrone induced parkinsonism (EP), we were the first who examined eye movements and found that it was possible to identify between this toxic Parkinson's syndrome and PN on the basis of a videooculography. In EP patients, we described velocity decsrease and hypometry in horizontal saccades, prolonged latency in horizontal saccades, and higher error rate in the antisacadic task. Behavioral disorder in REM sleep (RBD) as a prodromal stage of PN leads to impaired eye movement. In the evaluation with PN patients, we...
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The role of accumulation of iron and other metals in the pathophysiology of neurodegenerative diseases
Mašková, Jana ; Dušek, Petr (advisor) ; Vymazal, Josef (referee) ; Bártová, Petra (referee)
The role of metal accumulation in the pathophysiology of neurodegenerative diseases has been a hot topic in recent years due to the possibility of its treatment by chelating agents. Although the mechanisms of neurodegeneration are well known, the role of metal accumulation is still unclear. The main limitation are unsatisfactory methods for in vivo metal imaging; the most widely used technique is magnetic resonance imaging (MRI). Our aim was to assess the possibility of using transcranial sonography (TCS) in differential diagnosis of neurodegenerative diseases and to further explore the underlying factors of echogenicity. In the first study, using TCS fusion with MRI, we focused on location verification of the commonly assessed structures (substantia nigra and nucleus lentiformis) and exclusion of possible focal structural changes affecting the echogenicity in WD and PD patients. Moreover, obtained MRI were used for semi-quantitative comparison with TCS images. Although TCS has been confirmed to be highly beneficial in differential diagnosis of Wilson's disease and it should be recommended as a screening method for extrapyramidal patients with atypical course of the disease, the direct relationship between TCS and metal deposits could not be proven. The obtained results from the ultrasound fusion...
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Optical coherence tomography in multiple sclerosis.
Lízrová-Preiningerová, Jana ; Kubala Havrdová, Eva (advisor) ; Vymazal, Josef (referee) ; Taláb, Radomír (referee)
Spectral domain optical coherence tomography (SD-OCT), a non-invasive imaging method, is based on an analysis of a near-infrared light deflected from tisssue layers, that provides detailed images of retinal structures. Nerve cells of the retina, that originate from neuroectoderm, reflect neurodegeneration of the central nervous system (CNS), as well as acute damage of nerve structures caused by optic neuritis. The dissertation first presents established imaging protocol and quality standards for SD-OCT imaging in multiple sclerosis (MS). In the following section we introduce SD-OCT as a biomarker in MS. In a multicentric cross-sectional study, we had shown, that a single time measurement of peripapillary retinal nerve fiber layer thickness (RNFL) has a predictive value for a risk of disease progression in the next five years. Patients with a thickness of RNFL in the lowest tercile of the studied population had a relative risk of disease progression 2x higher than patients in the highest tercile. The second presented study tests whether the history of optic neuritis (ON) in MS is a risk factor for neurodegeneration of RNFL in later years. The study confirmed that long term changes of RNFL thickness in eyes post-ON and in eyes with no history of ON are not different. Therefore, we conclude that both,...
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Spatial Navigation Impairment as An EarlyMarker of Neurodegenerative Disease
Mokrišová, Ivana ; Hort, Jakub (advisor) ; Stuchlík, Aleš (referee) ; Vymazal, Josef (referee)
Aging of population with related increase of incidence of neurodegenerative diseases mostly Alzheimer disease (AD), poses a serious socioeconomic problem. In the recent years, research has been focused on specific early disease markers and identifications of patient's populations at increased risk of AD, which comprise mild cognitive impairment (MCI) and subjective cognitive decline (SCD) which may represent prodromal and preclinical stage of AD, while still preserving functional capacity. This thesis summarizes and further extends current knowledge in the field of AD with a specific focus on early disease markers. The main topic of the thesis is spatial navigation, especially its allocentric component and path integration. Examination of spatial navigation might serve as the valuable diagnostic tool which could be used in wider clinical practice for timely diagnostics, disease monitoring and also for evaluation of the treatment effect. We also present here experimental tests (questionnaires of subjective spatial navigation complaints and tests of visual perception) that have enough sensitivity and specificity for identification of subjects at risk for AD.
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