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Dissertationen zum Thema „Magnetické látky“
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1
Horký, Jakub. „Remanentní magnetismus elektromagnetů stejnosměrných stykačů“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442794.
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The master thesis is focused on a remanent magnetism of electromagnets of DC contactors. In the first part of the thesis deals with the formation of a magnetic field in different kinds of materials, description of their magnetization and sorting. The next part is focused on the principle and history of an electromagnet. Negative effects and remanent induction of the contactor are described in the end of the theoretical part. The second part is a practical part. First, the reaction times were measured on a pair of DC contactors. Using the obtained data, an electronic circuit was designed to minimize the difference in switching times of the given DC contactors.
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Minsterová, Alžběta. „Srovnání preklinických DCE-MRI perfusních technik“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242190.
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This diploma thesis deals with DCE-MRI (Dynamic Contrast-Enhanced Magnetic Resonance Imaging) thus one of the contrast magnetic resonance imaging methods. It describes the principle of conventional continuous DCE-MRI, which uses single bolus of contrast agent and further it focuses on the dual bolus contrast agent techniques, especially the interleaved acquisition. The graphical interface for processing Bruker systems data was made. Synthetic data were used to evaluate the influence of this method on the perfusion parameters estimation. Simulations proved that the further the second bolus is from the first one, the better results are. Simulations of acquisition interruption did not lead to the clear result. However, two statements, which are expected to lead to as good estimation of perfusion parameters as possible, were formulated
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Černý, Štěpán. „Využití multi-echo sekvencí pro DSC-MRI“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242109.
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The task of this thesis is to study the subject of perfusion analysis based on dynamic imaging with T2/T2* contrast. The focus was on the acquisition commonly used for DSC-MRI and especially in the acquisition pulse sequences that use images with different echo time, so called Multi-echo sequence. Principles of dynamic measurement by magnetic resonance imaging, the role of contrast agents and their influence on the relaxation times are described. It also describes the problems perfusion analysis, measurement and mathematical modeling parameters entering to the convolution dependency for getting perfusion parametersIn the experimental part is developed automatic algorithm to gain curves relaxation time T2 *. Next, the synthetic data are created and tested robustness estimate perfusion parameters against noise. In the next phase of work there are compared real scanned objects with using a conversion with T2 * and free of T2*. In the last phase of work is compared influence of length of used echo times on concentration curves and after perfusion analysis influence on resulting perfusion parameters.
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Bačovský, Jaromír. „Zvýraznění kontrastu pro rozlišení tkání a detekci kontrastních nanočástic metodami magnetickorezonančního zobrazování“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230830.
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Magnetic resonance imaging is a routine and powerful diagnostic technique capable of providing detailed information about the structure and composition of the tissues. This diploma thesis is concerned with the mechanisms of contrast origin and contrast modifications by molecular and nanoparticle contrast agents. First sections of the thesis summarize basic knowledge about pulse sequences and it aims to provide an overview on MRI contrast agent with a special emphasis on paramagnetic gadolinium contrast agents and superparamagnetic nanoparticles. The main purpose of this study is to develop the software called MRICalc, which is able to optimize contrast in MRI images. Based on analysis of signal formula of typical pulse sequences, MRICalc is able to propose the parameters of the pulse sequence for compartment-specific enhancement of the contrast. User chooses from the list of the samples and after calculation he obtains the values of echo time, repetition time and flip angle, all of which simultaneously seem to create the appropriate setting to enhance the contrast. MRICalc also allows to plot contrast function with respect to the chosen parameter. Software, including its graphical user interface, is designed in Python. The sample consists from solution of CuSO4 and distilled water was designed to verify the correct function of MRICalc. Sulphate represents a contrast agent. Preclinical MR system Bruker BioSpec 94/30 USR located at Institute of Scientific Instruments of the ASCR, v.v.i was used to measure contrast curve of FLASH pulse sequence, which is a typical representative of gradient echo. Results of the measurement were compared to the theoretical model provided by MRICalc.
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Kudlička, Petr. „Metody akvizice pro DCE-MRI“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220035.
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In my master’s thesis I describe basics of magnetic resonance measurement. I focus on methods of DCE-MRI with T1 weighting image. I mention some basic contrast agents which are used in MRI imaging. I describe some of pulse sequences which are used in experimental part of my thesis. There I measure contrast in the sample. The measurement is performed in accordance with an acquisition protocol I have proposed. The experiment part was realized on 1.5 T magnet at Masaryk Oncological Institute in Brno. I improved software which is use to research of MR IR TurboFLASH’s data and made software which is use to evaluation perfuse analysis ours measured sequences. At the end I made a discussion about gained facts.
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Macíček, Ondřej. „Pokročilé metody perfuzní analýzy v MRI“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-410312.
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This dissertation deals with quantitative perfusion analysis of MRI contrast-enhanced image time sequences. It focuses on two so far separately used methods -- Dynamic contrast-enhanced MRI (DCE-MRI) and Dynamic susceptibility contrast MRI (DSC-MRI). The common problem of such perfusion analyses is the unreliability of perfusion parameters estimation. This penalizes usage of these unique techniques on a regular basis. The presented methods are intended to improve these drawbacks, especially the problems with quantification in DSC in case of contrast agent extravasation and instability of the deconvolution process in DCE using advanced pharmacokinetic models. There are a few approaches in literature combining DCE and DSC to estimate new parameters of the examined tissue, namely the relaxivity of the vascular and of the interstitial space. Originally, in this scheme, the 2CXM DCE model was used. Here various models for DCE analysis are tested keeping in mind the DCE-DSC combination. The ATH model was found to perform better in this setting compared to 2CXM. Finally, the ATH model was used in alternating DCE-DSC optimization algorithm and then in a truly fully simultaneous DCE-DSC. The processing was tested using simulated and in-vivo data. According to the results, the proposed simultaneous algorithm performs better in comparison with sequential DCE-DSC, unleashing full potential of perfusion analysis using MRI.
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Krchňavý, Jan. „Akvizice a předzpracování MRI obrazových sekvencí pro klinické perfusní zobrazování“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219512.
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This thesis describes the theory for static and dynamic magnetic-resonance imaging using contrast agents affecting T1 relaxation time. The available acquisition methods in the specified facility of Masaryk Oncological Institute in Brno are described. The sequences for subsequent experimental measurements are selected. The used phantoms are described. Acquisition protocol for measuring is described briefly and the evaluation method for the measured data is suggested. The best acquisition sequence and a method of measurements is chosen influenced by estimation of relaxation time T1, sensitivity and signal to noise ratio. Perfusion analysis is executed and perfusion parameters are calculated. The work was supported by the European Regional Development Fund and the State Budget of the Czech Republic (RECAMO, CZ.1.05/2.1.00/03.0101).
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Krchová, Tereza. „Responzivní kontrastní látky pro tomografii magnetické rezonance (MRI)“. Doctoral thesis, 2017. http://www.nusl.cz/ntk/nusl-357606.
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ABSTRACT This work is focused on the synthesis of a family of new macrocyclic ligands with exchangeable protons on coordinating groups that could potentially serve (after complexation with suitable paramagnetic lanthanide(III) ions) as responsive contrast agents (CAs) for magnetic resonance imaging (MRI). It is expected that measurement of extracellular pH should bring information for tumorous disease diagnoses and/or for suggesting the most efficient treatment. Therefore, our attention was focused on pH-dependent CAs based on a PARAmagnetic Chemical Exchange Saturation Transfer (PARACEST) mechanism capable of reporting pH changes in tissue. The PARACEST-related properties of a series of Ln(III) complexes with the CEST effect caused by amino groups coordinated to the central Ln(III) metal ions were investigated. Such a kind of PARACEST CA is new and has had no precedent in the literature. It was shown that these Ln(III) complexes produce a pH-sensitive PARACEST effect in the pH region relevant for living systems. The study brings proof-of-principle for utilization of complexes with a linear diamine pendant arm, i.e. complexes with two exchanging proton pools, for ratiometric pH determination by MRI independently on the probe concentration. In addition, to ensure a higher kinetic inertness of the...
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Koucký, Filip. „Kontrastní látky pro heteronukleární MRI“. Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-380886.
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In this thesis the pH dependency of the coordination modes of lanthanide complexes with macrocyclic ligands based on 1,4,7,10-tetraazacyclododecane skeleton was studied. The cyclen-based ligand structures in this work contained three acetate and one aminoethyl group with a N-alkyl-N-methylphosphonate substituent, DO3AN(R)P, where R is an alkyle substituent on the nitrogen atom of the pendant arm (R = methyl, benzyl). Lanthanide complexes of a previously studied prototype ligand DO3ANP with secondary amino group (R = H) have shown interesting properties in the field of 31 P NMR imaging because of their various coordination properties, which allow in situ pH measurement. These complexes can also be used for monitoring the kinetics of the chemical exchange of the amino group proton in 1 H NMR imaging using the chemical exchange saturation transfer (CEST NMR). In this thesis, two new derivatives DO3ANMeP and DO3ANBnP were prepared in order to better understand the coordination modes changes in this ligand series. Also, their coordination behaviour with selected lanthanide ions was studied (Eu3+ , Gd3+ , Dy3+ , Yb3+ ). Based on a series of NMR and luminescence measurements, it was found out, that in acidic conditions the complexes containing DO3ANP motif bind a water molecule in their coordination...
10
Špánek, Jiří. „Koordinační sloučeniny jako kontrastní látky pro 19F MRI“. Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-388728.
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Magnetic Resonance Imaging (MRI) is one of noninvasive imaging and diagnostic methods in today's medicine. The most commonly measured nucleus is H1 of the water molecules present in the human body. There are also methods that use signal saturation transfer between the contrast agent and water molecules via exchangeable H1 nuclei, or use a different nucleus like F19 . Compounds that show a high potential in this area are complexes of paramagnetic ions such as Gd3+ , Eu3+ , Co2+ , Cu2+ and Ni2+ , which can affect relaxation times and chemical shifts of other atoms due to their magnetic properties. This Master's thesis focuses on ligands L1 and L2 which were prepared in the Bachelor thesis. The main focus is on preparation of complexes with selected paramagnetic ions and subsequent study of their properties relevant for a potential use as contrast agents for F19 -MRI and CEST methods. Keywords: F19 -MRI, CEST, macrocyclic ligands, coordination chemistry
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Mrklovský, Milan. „Detekce a charakterizace ložiskových lézí jater hepatocytárního původu pomocí magnetické rezonance s použitím hepatospecifické kontrastní látky Gd-EOB-DTPA“. Doctoral thesis, 2012. http://www.nusl.cz/ntk/nusl-311799.
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Detection and characterization of hepatocellular liver lesions by using MRI with hepatospecific contrast agent Gd-EOB-DTPA Aim: To prospectively compare contrast properties of extracelullar (gadobutrol) and hepatospecific (gadoxetic acid) contrast agents in upper abdominal MRI studies. To prospectively evaluate the possibilities of detection and characterization of hepatocellular liver lesions by means of MRI using hepatospecific contrast agent Gd-EOB-DTPA. Materials and methods: Standardized (0,1 ml/kg) dose of gadobutrol (56 subjects) and gadoxetic acid (51 subjects) was administered intravenously by MRI-compatible injector at 2 ml/s, followed by 20 ml saline flush. MR signal intensity changes (SIC) between precontrast scans and arterial phase, portal venous phase, equilibrium, and delayed scans at 10 and 20 minutes were measured in abdominal aorta, portal vein, common bile duct, liver, and spleen. Mean SIC values for gadobutrol and gadoxetic acid were compared by a two-sample t-test with p-value < 0,05 considered significant. A total of 78 subjects with known arterial hypervascularized liver lesion (other than haemangioma) were examined on MRI with administration of liver specific contrast agent Gd-EOB-DTPA. All studies were performed before and after contrast agent injection in arterial, portal...
12
Popr, Martin. „Syntéza derivátů beta-cyklodextrinu pro medicinální aplikace“. Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-297764.
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Synthesis of monosubstituted β-cyclodextrin derivatives for medicinal applications Abstract This thesis is focused on preparation of a set of β-cyclodextrin derivatives with potential use as scaffolds for a construction of novel MRI contrast agents. Firstly, the skeleton of native β-CD was selectively persubstituted at possitions 6 and equipped with azide functions. Per-6-azido-β-CD was then monosubstituted on secondary face of the macrocycle. (E)-cinnamylbromide and propargylbromide were chosen as suitable reagents. The monosubstitution reaction afforded two types of regioisomers, substituted at position 2I -O- or 3I -O-. These regioisomers were sucessfully separated via preparative column chromatography after peracetylation of all free hydroxyl groups. 2I -O-, 3I -O-formylmethyl- and 3I -O- karboxymethyl- analogues were prepared by oxidative transformation of cinnamyl group. Finally the usability of the formylmethyl- derivative for covalent binding with suitable substrate via reductive amination was confirmed. Keywords: cyclodextrins, monosubstitution, cinnamyl, propargyl, formylmethyl, carboxymethyl, reductive amination, MRI, contrast agents
13
Martinisková, Marie. „Kontrastní látky pro 19F nukleární magnetickou tomografii“. Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-348668.
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The aim of this Master Thesis is to synthesize and study new macrocyclic ligands containing fluorine atoms for use as potencial contrast agents in 19 F magnetic resonance imaging. New ligands were designed as analogues of ligands used in contrast agents already utilized in clinical practice - macrocyclic ligand for complexation of trivalent lanthanide ions based on DOTA skeleton and series of macrocyclic ligands for complexation of divalent nickel ion based on cyclam skeleton. All designed ligands were synthesized a characterized. The complexes [LnIII (dotptfe )]− were tested in vitro and in vivo to study 19 F NMR relaxation times enhancements.
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Pechrová, Zdislava. „Funkční nanodiagnostika pro 31-P zobrazování magnetickou rezonancí: Nové paradigma pro kontrastní látky“. Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-397025.
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The topic of my Master degree thesis is the development of a conceptually new class of contrast agents for the 31P magnetic resonance imaging (31P MRI). These agents are based on nanoparticles of calcium(II) phytate. Phytate (myo-inositol-1,2,3,4,5,6-hexakisphosphate) is largely present in plants, seeds and grains. It is non-biodegradable but nontoxic for animals and human beings and most importantly around 22% of its mass is phosphorus, so it is easily detectable by 31P NMR/MRI. These nanoparticles of Ca(II) phytate were doped with paramagnetic Fe3+ ions which broaden the 31P signal, making the nanoparticles invisible in healthy tissues. In the presence of bacteria producing siderophores (for example in Helicobacter pylori in gastric ulcers), Fe3+ is released from the gel and 31P MRI signal becomes detectable. In vitro simulation of this release was performed with deferroxamine, a compound possessing high affinity to Fe3+ ions forming coloured complex with it exploitable for the UV-VIS evaluation. The Ca(II) phytate can be synthesized in two possible ways. The first way is by direct precipitation of the Ca2+ salt with sodium phytate. The second way is ion exchange of phosphate in the nanoparticles of hydroxyapatite which creates electrostatically stabilized calcium phytate nanoparticles. Both...
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Kačenka, Michal. „Feromagnetické nanočástice perovskitového typu“. Doctoral thesis, 2015. http://www.nusl.cz/ntk/nusl-350057.
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Kikerlová, Soňa. „Multimodální T2 kontrastní látky na bázi fluorescenčně značených magnetických jader spinelového typu pro zobrazování magnetickou rezonancí“. Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-388731.
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This diploma thesis was focused on the preparation of magnetic and fluorescently labelled spinel type nanoparticles, specifically nanoparticles of zinc-doped cobalt ferrite intended for application in magnetic resonance imaging and fluorescence microscopy in experimental practice. In previous studies, various ferrite nanoparticles exhibited relatively high transverse relaxation times and strong negative T2 contrast. These properties were also supposed for the zinc-doped cobalt ferrite nanoparticles. This assumption was confirmed by studying their magnetic and contrasting properties. Fluorescence properties of the prepared nanoparticles were also successfully studied. With respect to the intended applications of these particles, the issue of suitable surface modification of magnetic cores, their colloidal stabilization in an aqueous suspension and toxicity in biological systems were studied. Key words: nanoparticles, ferrites, MRI, relaxation
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Drahoš, Bohuslav. „Potenciální kontrastní látky pro MRI založené na komplexech manganu(II)“. Doctoral thesis, 2011. http://www.nusl.cz/ntk/nusl-311569.
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The thesis is focused on the synthesis and characterization of novel Mn2+ complexes as alternative to Gd3+ chelates which are wide-spread contrast agents in Magnetic Resonance Imaging (MRI). In the perspective to find suitable chelators of Mn2+ , three groups of pentadentate ligands with different size of macrocylic cavity, different donor atoms and number of pendant arms containing various functional groups have been investigated. Coordination numbers of 6 or 7 were found in the crystal structure of the Mn2+ complexes enabling binding of one or two water molecules in the first coordination sphere. The direct water coordination causes a decrease in the complex stability and thus, the thermodynamic stability of investigated chelates is lower than that of polyaminocarboxylate complexes and their dissociation is very fast in comparison to [Mn(nota)] and [Mn(dota)]2- . The studied Mn2+ complexes do not undergo oxidation in air except for complexes with 12-membered ligands which are oxidized to Mn3+ species. The proton relaxivities of the bishydrated complexes are two times higher than those for monohydrated complexes and are comparable to those of commercial contrast agents based on Gd3+ complexes. Variable-temperature 17 O NMR data revealed that the water exchange varies from slow to intermediate or...
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Krijt, Matyáš. „Značení T buněk bimodální kontrastní látkou pro studium mrtvice in vivo“. Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-305768.
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Stroke is a serious brain injury, which causes sudden death or terminates in permanent neurological disability. Nowadays, tissue plasminogen activator (tPA) is used as the only effective treatment of stroke. One of the potential targets for novel therapy are T cells. Even though the explicit role of T cells in the pathogenesis of brain injury, amounts and timing of all T cell subtypes infiltrating into brain during the stroke still needs further investigation. The research in this field is complicated by the lack of efficient methods for in vivo cell tracking. Therefore the aim of this thesis was to develop a method of T cells labelling by MRI contrast agent in order to investigate T cells distribution in ischemic mice model using in vivo MR imaging. T cells were isolated from C57/BL6 mice in two step isolation protocol using gradient centrifugation and magnetic separation with the efficiency of 97 %. The isolated cells were labelled with 100 μg Fe/mL of Molday ION Rhodamine B contrast agent. The labelling efficiency after 17 hours of cells incubation was higher than 99 %. The labelled cells were cultured with CD3 and CD28 antibodies resulting into the 74 % viability of labelled T cells compared to 83 % viability of non labelled T cells. The labelled T cells were visualized by fluorescent...
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Gálisová, Andrea. „Alternativní metody zobrazení pankreatických ostrůvků“. Doctoral thesis, 2018. http://www.nusl.cz/ntk/nusl-382748.
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Transplantation of pancreatic islets (PIs) represents an alternative treatment for type 1 diabetes mellitus. Post-transplant monitoring of islets by a reliable imaging method may contribute to the improvement of the transplantation outcome. In this thesis, novel visualization approaches for PIs were tested using magnetic resonance (MR) and optical imaging on phantoms and experimental animals, including Chemical Exchange Saturation Transfer (CEST) MR, fluorine (19 F) MR, bioluminescence and fluorescence imaging. MR imaging based on frequency-selective method CEST was performed on islets labeled with Eu-/Yb-based chelates. Labeled islets possessed low MR signal in phantoms, what would have been unsatisfactory for in vivo applications. Moreover, viability and function of labeled islets was impaired reflecting limited applicability of these agents for islet labeling and visualization. Genetically modified bioluminescent islets showed suitable properties for longitudinal tracking of their post-transplant fate at an artificial transplant site - subcutaneously implanted polymeric scaffolds. Using multimodal imaging (MR and bioluminescence), the optimal timing for transplantation of islets into the scaffolds was assessed in diabetic rats. Islets transplanted into scaffolds using the optimized timing scheme...
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Mikulecká, Jana. „Vývoj analytických metod pro stanovení fosforylovaných složek bakteriálních buněčných membrán“. Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-324659.
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Phospholipids are dominant components of bacterial cell membranes, where they create double layers. Bacteria differ in their phospholipid composition determination of which can help in identification of important groups of microorganisms. Phospholipid composition of bacteria is influenced by many environmental factors, therefore its variation can be observed within one bacterial stem also. Because of its simplicity, thin layer chromatography is usually applied to identification and determination of bacterial phospholipids. Disadvantage of this method are the high demands of time, carefulness and skills of the analytical personnel. The increasing interest in the phospholipid double-layer promotes the detailed investigation of their fatty acid composition because the more detailed analyses allows for more information yield about bacteria. Gas chromatography hyphenated with mass spectrometry seems to be the best choice for these purposes. Fatty acid identity and total fatty acid content in phospholipid molecules could be determined by this method. Additionally, number, position and isomerism of double bonds and presence of other functional groups on hydrocarbon chain could be determined. Whereas a suitable and...