|
|
Titaniun Dioxide - Phosphonate Assemblies as Medical Nanoprobes
Řehoř, Ivan ; Lukeš, Ivan (advisor) ; Lang, Kamil (referee) ; Peters, Joop (referee)
Titanium Dioxide - Phosphonate Assemblies as Medical Nanoprobes Ivan Řehoř PhD. Thesis Abstract: Multimodal imaging-therapeutic nanoprobe TiO2@RhdGd was prepared and successfully used for in- vitro and in-vivo cell tracking as well as for killing of cancer cells in-vitro. TiO2 nanoparticles, 12 nm in diameter, were used as a core for phosphonic acid modified functionalities, responsible for contrast in MRI and optical imaging. The phosphonic acid derivatives, used for surface modification, allows for grafting extraordinarily high loads of irreversibly adsorbed molecules of both types in one step. The prepared probe shows very high 1 H r1 relaxivity value as well as relaxivity density value, both crucial parameters for its use in MRI. The presence of fluorescent dye in its structure allows for its visualization by means of fluorescence microscopy. The applicability of the probe was studied, using three living systems - mesenchymal stem cells, cancer HeLa cells and T-lymphocytes. The probe did not exhibit toxicity in any of these systems and its long time storage in a lysosomal compartment was confirmed. Labeled cells were successfully visualized in-vitro by means of fluorescence microscopy and MRI. Consequent visualization of labeled cells in-vivo by means of fluorescence microscopy was also achieved....
|
|
|
Potential contrast agents for MRI based on manganese(II) complexes
Drahoš, Bohuslav ; Lukeš, Ivan (advisor) ; Geraldes, Carlos F. G. C. (referee) ; Toth, Imre (referee)
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...
|
|
|
Increasing Resolution in Perfusion Magnetic Resonance Imaging Using Compressed Sensing
Mangová, Marie ; Polec,, Jaroslav (referee) ; Šmídl, Václav (referee) ; Rajmic, Pavel (advisor)
Perfusion magnetic resonance imaging is a medical diagnostic method which requires high spatial and temporal resolution simultaneously to capture dynamics of an intravenous contrast agent which is used to perfusion measurement. However, magnetic resonance imaging has physical limits which do not allow to have this resolution simultaneously. This thesis deals with compressed sensing which enables to reconstruct measured data from relatively few acquired samples (below Nyquist rate) while resolution required to perfusion analysis is increased. This aim could be achieved with suitably proposed apriory information about sensed data and model proposal. The reconstruction is then done as an optimization problem. Doctoral thesis brings several new reconstruction models, further proposes method to debias this estimates and examines influence of compressed sensing onto perfusion parameters. Whole thesis is ended with extension of compressed sensing into three-dimensional data. Here, the influence of reconstruction onto perfusion parameters is also described. In summary, the thesis shows that due to compressed sensing, temporal resolution can be increased with the fixed spatial resolution or spatial resolution can be increased with the fixed temporal resolution.
|
|
|
Measurement of diffusion coefitients by use of magnetic resonance
Král, Jakub ; Gescheidtová, Eva (referee) ; Bartušek, Karel (advisor)
This Bachelor thesis is focused on imaging techniques based on the principles of nuclear-magnetic resonance. These techniques are one of the most modern studies of physical, chemical and biological properties of substances. Introduction of this work is focused primarily on physical principles. Further in this work attention is given to the method of the PFG-SE but also to more modern multiinterval NMR methods, which removes the systematic measurement errors for heterogeneous materials. Part of the work is also devoted to b-factor calculations for various kinds of pulse sequences. In last part the work is devoted to data processing in Matlab and Marevisi. Selected method from the beginning of the work is than used to measure the diffusion and processing of tissue cultures.
|
|
|
Modelling of parametric arterial input function in perfusion imaging
Černý, Štěpán ; Jiřík, Radovan (referee) ; Kratochvíla, Jiří (advisor)
The task of this bachelor’s tesis is to study the subject in the area of perfusion imaging based on dynamic imaging with T1 contrast. Aims is primarily on the role of the arterial input function. Principles phenomenon of dynamic magnetic resonance measurements are discribed. The role of contrast media and their influence on the relaxation time T1 are described. It is also described problems perfusion analysis, measurement and mathematical modeling of arterial input function and perfusion acquisition parameters. In the experimental part, there is modeled several models of arterial input function and their evaluation. Further the creation program for the approximation real measurement of arterial input function created models and the integration of this program into a graphical interface created for work with models. Was also verified the functionality of the program and evaluate the success of approximations for individual models.
|
|
|
Scaling of arterial input function in DCE-MRI
Holeček, Tomáš ; Kolář, Radim (referee) ; Kratochvíla, Jiří (advisor)
Perfusion magnetic resonance imaging is modern diagnostic method used mainly in oncology. In this method, contrast agent is injected to the subject and then is continuously monitored the progress of its concentration in the affected area in time. Correct determination of the arterial input function (AIF) is very important for perfusion analysis. One possibility is to model AIF by multichannel blind deconvolution but the estimated AIF is necessary to be scaled. This master´s thesis is focused on description of scaling methods and their influence on perfussion parameters in dependence on used model of AIF in different tissues.
|
|
|
Using multi-echo sequences in DSC-MRI
Černý, Štěpán ; Jiřík, Radovan (referee) ; Macíček, Ondřej (advisor)
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.
|
|
|
Segmentation of the kidney from the renal perfusion MR image sequences
Jína, Miroslav ; Walek, Petr (referee) ; Malínský, Miloš (advisor)
This master’s thesis deals with kidney segmentation in perfusion magnetic resonance image sequences. Kidney segmentation is carry out by a few methods such as regionbased techniques, deformable models, specimen-based methods, edge-oriented methods etc. The universal algorithm for patient kidney segmentation still does not exist. Proposed method is an active contour Snake, which is created in programming environment MatLab. Final contours are quantitatively and visually compared to manual kidney segmentation.
|
|
|
Optimization of the MRI chicken embryos measurements
Sedláčková, Gabriela ; Dražanová, Eva (referee) ; Krátká, Lucie (advisor)
This thesis deals with optimization of MRI measuring of phantoms containing the chicken embryo. The theoretical part of thesis is dedicated to the MRI fundamentals and description of pulse sequences. In the next part the options of keeping and monitoring the temperature are being discussed. The thesis also deals with design and realization of phantoms which are used for measuring. A browser of images captured by MRI was programmed in Matlab environment. The program allows users to look through the images with different settings of pulses sequences or kind of phantom. The final part of thesis describes the anatomical structures of chicken embryo and discussion of collected results.
|
|
|
Image processing of MRI
Němcová, Simona ; Jiřík, Radovan (referee) ; Krátká, Lucie (advisor)
This thesis deals with the cartilage imaging using magnetic resonance. At first, there is mentioned physical principle of the magnetic resonance phenomenon and the most commonly used excitation sequences, followed by the description of the 9.4 T MR imaging system Bruker BioSpec 94/30 USR, which was used for measurement in the practical part. The next part is dedicated to the composition of cartilages and describes the temporomandibular joint, due to its suitability as an object for cartilage imaging. The series of MR scans of temporomandibular joint were taken with different acquisition parameters and evaluated by program designed through the MATLAB software. The program can be used for viewing scanned images, evaluating their contrast and determining the T1 relaxation time of the tissues by creating T1 maps.
|
guest ::
