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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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Coronary atherosclerosis imaging using CT coronary angiography in patients with high risk of coronary heart disease
Baxa, Jan ; Ferda, Jiří (advisor) ; Vymazal, Josef (referee) ; Mechl, Marek (referee)
Coronary atherosclerosis imaging using CT coronary angiography in patients with high risk of coronary heart disease Coronary heart disease (CHD) belongs to most frequent disorders and in industrial countries is responsible for most deaths in population. The costs of treatment of the clinical manifested CHD are high, so there is tendency to detect this disease in early phase and ideally before development of clinical symptoms. Aim of our study was to evaluate the value of coronary CT angiography (CCTA) in detecting of coronary atherosclerosis in early (preclinical) phase. Our goals were estimation of prevalence of atherosclerosis in group, influence of main risk factors on grade and character of atherosclerotic changes. In follow-up we concerned on occurrence of cardiac events. 205 patients with increased cardiovascular risk underwent CCTA using dual-source CT. Coronary findings were analyzed by character of atherosclerotic changes and degree of event. stenosis. Statistical evaluation of influence of risk factors was made using the odds ratio. The statistically important differences were tested between subgroup of type 2 diabetics and non-diabetics. All patients were under follow-up for two years. Overall prevalence of atherosclerosis in analyzed group was 73 %, calcified lesions were found in 63.9 %...
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Mesial temporal epilepsy: comparison of morphological changes after different neurosurgery approaches with clinical seizure outcome
Malíková, Hana ; Vymazal, Josef (advisor) ; Kršek, Pavel (referee) ; Hájek, Milan (referee)
Background: Mesial temporal lobe epilepsy (MTLE) is the most surgically amenable epilepsy diagnosis and the results of epilepsy surgery are clearly superior to prolonged medical therapy. Stereotactic radiofrequency amygdalohippocampectomy (SAHE) is an alternative therapy of MTLE to the open neurosurgery approaches. In our hospital SAHE has been used since 2004. We produced lesions from the occipital access with a single trajectory in the long axis of amygdalohippocampal complex (AHK) using the probe with a flexible active tip. The aim of this study was to correlate the morphological changes after different neurosurgical approaches including volume reduction of the target structures / the hippocampus, the amygdala, entorhinal (EC) and perirhinal (PRC) cortices/ with the clinical seizure outcome. Methods: We included 26 consecutive patients, who underwent SAHE using Leksell stereotactic system and 10 patients treated by microsurgical amygdalohippocampectomy (AHE). MR volumetry of hippocampus, amygdale, EC and PRC was performed 1 year after the procedure. The clinical outcome was assessed 2 years after the procedure according to Engel's Classification. Results: No serious adverse events occurred after both procedures. One year after SAHE, the hippocampal volume decreased by 55.5 18.0% (p<10-4 ), the...
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Predictive markers for development of clinical status in multiple sclerosis patients.
Horáková, Dana ; Kubala Havrdová, Eva (advisor) ; Vymazal, Josef (referee) ; Ambler, Zdeněk (referee)
Multiple Sclerosis is a chronic neurological disease that, without therapy, causes a serious disability in a substantial number of patients. We are not able to cure the disease yet, but with current repertoire of drugs we are able to significantly influence the inflammatory part of the disease and if patients response to a therapy, we can fundamentally change their prognosis. The treatment must be started early, i. e. in a phase when axons are still preserved, optimally in a clinically isolated syndrome. A great issue at this stage is to properly estimate the prognosis of an individual patient and to choose the right treatment for the right patient. Moreover, after the start of the treatment, it is very important to carefully monitor the patient's treatment response. Among the surrogate markers that are available today, MRI is one of the most utilised in an everyday practice. Our work is trying to find the answer to the question what is the evolution of total and regional brain atrophy and which MRI parameters best reflect clinical status of an MS patient. We analysed 2- and 5-year clinical and MRI data of 181 patients from the original ASA (Avonex-Steroids-Azathioprine) study. In accordance with other papers we confirmed significant brain atrophy already in the early phase of the disease. This total...
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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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Cardiovascular involvement in patients with Fabry disease
Jirák, Daniel ; Hájek, Milan (advisor) ; Vymazal, Josef (referee) ; Žižka, Jan (referee)
The evaluation of clinical magnetic resonance (MR) images is influenced by errors (subjective evaluation, noise, etc.). It is possible to eliminate these errors by using certain mathematical and statistical methods. One of these methods is texture analysis (TA), which can describe images quantitatively by computed texture parameters. The aim of this thesis was to analyze MR images of various subjects (phantoms, apples, calf muscles, livers) by TA and to evaluate its possible use in clinical practice. The main tasks of the thesis were: 1) to develop a new phantom suitable for TA and MR imaging that is biochemically and mechanically stable 2) to optimize an algorithm for TA parameter selection and classification 3) to apply TA in evaluating MR images. The first methodical part of the thesis deals with the optimization of texture parameter selection and texture classification. For this purpose a new type of phantom was developed. This PSAG phantom, with a nodular structure from polystyrene spheres (PS) placed into agar (AG), is suitable for MR imaging and for TA because it produces a strong MR signal and because its T1 and T2 relaxation times are in the range of biological tissue and can be easily modified by employing various densities of PS spheres or by the addition of a contrast agent. Measurements of PSAG...
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