National Repository of Grey Literature 70 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Comparison of Pharmacokinetic models for DCE-MRI
Bačovská, Kristýna ; Mézl, Martin (referee) ; Jiřík, Radovan (advisor)
This thesis deals with perfusion analysis using DCE-MRI (Dynamic contrast-enhanced magnetic resonance imaging). DCE-MRI is commonly used for microcirculation evaluation mainly in oncology and in recent years also in cardiology. The theoretical overview focuses on the issue of pharmacokinetic modeling and the estimation of perfusion parameters using selected models. The experimental part describes research software PerfLab and then it is aimed at the proposed program for synthetic data generation. Simulated data obtained under ideal conditions and in the presence of noise were used to compare models for the accuracy and reliability of DCE-MRI analysis.
Quantification of Relaxation Time T1 in DCE-MRI
Vitouš, Jiří ; Mézl, Martin (referee) ; Jiřík, Radovan (advisor)
This bachelor thesis deals with methods of T1 relaxation time quantification and B1 magnetic field inhomogeneities corrections. For purposes of the required measurements, the phantom was created using a 3D printer. Firstly the thesis presents information about a given theme, then it hands out the results of measurements taken using standard quantification methods. These methods are consequently analyzed and compared. Next part of the bachelor thesis deals with the fast method based on a variable flip angle (VFA), which needs a magnetic field B1 correction maps to give reasonable T1 estimates. For this purpose, two methods of B1 correction are presented. The first method is a double angle method and second is based on mapping magnetic field B1 using a reference T1 map. To decide which T1 map of which method should be used as a reference, a simple simulation is proposed, which describes the impact of unfavorable effects, such as B1 itself, on the T1 estimate of standard methods. In the end, the conclusions are made and the results of VFA methods are compared with standard methods of quantification.
Measurement and processing of diffusion data from magnetic resonance
Vankó, Bence ; Jiřík, Radovan (referee) ; Kolářová, Jana (advisor)
This bachelor thesis deals with DTI examination. The diffusion tensor model of magnetic resonance imaging is a modern diagnostic method mainly used to visualize the spatial relationship of a particular neuronal pathway of the brain. The work is divided into three main parts. The first part contains the theoretical introduction to MRI, DTI and literary research from individual scientific articles dealing with DTI experiments. The second part of the thesis deals with the search of electronic articles to choose the right acquisition. Based on the articles being studied, parameters were selected and polished during the measuring of the phantom. In the third part, the measurements are done on the basis of the resulting acquisition protocol and the data is processed in various software.
Comparison and assessment of single-echo and multi-echo BOLD fMRI acquisition
Kovářová, Anežka ; Jiřík, Radovan (referee) ; Mikl, Michal (advisor)
This master’s thesis deals with functional magnetic resonance and monitoring of the effect of acquisition acceleration methods on the quality of functional images and observed BOLD signal. The basic principles of magnetic resonance imaging, the explanation of the specifics of functional magnetic resonance and the formation and scanning of BOLD signal are described here. Subsequently, there is the definition of fMRI experiment and description of sequences used for fMRI, focusing on aquisition acceleration techniques. The influence of sequence parameters on image quality and the data processing methods are explained aftewards. The practical part describes the parameters of used sequences, the acquisition procedure and the task for the subject during aquisition. Data from 26 healthy volunteers were obtained and analyzed afterwards. Based on this, the differencesbetween the different sequence variants were evaluated and the initial assumption that the multi-echo acquisition yields better results with faster measurements than single-echo was confirmed.
Image reconstruction form projections
Gargulák, Dušan ; Kolář, Radim (referee) ; Jiřík, Radovan (advisor)
This semestral work deals with the principle of the image reconstruction from projections, which is the basis for the modern method of the RTG computed tomography (CT RTG). The work is above all focused on the Simple BackProjection and Filtered BackProjection. In the first part there are outlined theoretical principles, which explain Radon Transform and inverse Radon Transform. There is also cleared up the process of the Simple BackProjection. The next part of the work contains the practical aplications of Radon Transform and Simple BackProjection, which was made in MATLAB. There is described the script for the projection generating and the script for the Simple BackProjection process. As the last item there is annotated the graphic interface for the mentioned aplications.
Internet library of methods and algorithms used for medical image registration
Koňařík, Jakub ; Jiřík, Radovan (referee) ; Peter, Roman (advisor)
Image registration is a procedure which is heading to search for a geometric transformation, which ensures same position, orientation and size of coresponding objects in pictures. How does these methods work? These methods and principies are explained in first part of this work. Second part of this work is aimed to explain theory about information systems and practical creation of the internet databaze. These practical part was realized in editorial system called Drupal.
Ultrasound Image Sequences Segmentation
Kořínek, Peter ; Jiřík, Radovan (referee) ; Mézl, Martin (advisor)
When we scan image data by ultrasound, we have a little information of displayed scene. For understanding content of the image we try to separate the observed objects of interest from the background. Obtaining information of these objects is called a process called segmentation. This work is focused on the segmentation of ultrasound image sequences using geometric active contours solved by the method of level sets. For better representation is also dealing with image preprocessing. The result is an implementation of segmentation methods on simulated and real data.
Advanced Moment-Based Methods for Image Analysis
Höschl, Cyril ; Flusser, Jan (advisor) ; Papakostas, George (referee) ; Jiřík, Radovan (referee)
The Thesis consists of an introduction and four papers that contribute to the research of image moments and moment invariants. The first two papers focus on rectangular decomposition algorithms that rapidly speed up the moment calculations. The other two papers present a design of new moment invariants. We present a comparative study of cutting edge methods for the decomposition of 2D binary images, including original implementations of all the methods. For 3D binary images, finding the optimal decomposition is an NP-complete problem, hence a polynomial-time heuristic needs to be developed. We propose a sub-optimal algorithm that outperforms other state of the art approximations. Additionally, we propose a new form of blur invariants that are derived by means of projection operators in a Fourier domain, which improves mainly the discrimination power of the features. Furthermore, we propose new moment-based features that are tolerant to additive Gaussian image noise and we show by extensive image retrieval experiments that the proposed features are robust and outperform other commonly used methods.
Modeling and Signal Processing in Dynamic Contrast Enhanced Magnetic Resonance Imaging
Kratochvíla, Jiří ; Šroubek,, Filip (referee) ; Tintěra,, Jaroslav (referee) ; Jiřík, Radovan (advisor)
The theoretical part of this work describes perfusion analysis of dynamic contrast enhanced magnetic resonance imaging from data acquisition to estimation of perfusion parameters. The main application fields are oncology, cardiology and neurology. The thesis is focused on quantitative perfusion analysis, specifically it contributes to solving of the the main challenge of this method – correct estimation of the contrast-agent concentration sequence in the arterial input of the region of interest (arterial input function). The goals of the thesis are stated based on literature review and on the expertise of our group. Blind deconvolution is selected as the method of choice. In the practical part of this thesis, a new method for arterial input function identification based on blind deconvolution is proposed. The method is designed for both preclinical and clinical applications. It was validated on synthetic, preclinical and clinical data. Furthermore, possibilities of the longer temporal sampling provided by blind deconvolution were analyzed. This can be used for improved spatial resolution and possibly for higher SNR. For easier deployment of the proposed methods into clinical and preclinical use, a software tool for perfusion data processing was designed.
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.

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1 Jiřík, Rudolf
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