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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modelování v perfusním MR zobrazování / Modelling in perfusion MR imaging

Válková, Hana January 2014 (has links)
This thesis deals with the magnetic resonance perfusion data analysis especially DCEMRI. In its introduction the thesis describes the problem of DCE-MRI data aquisition, the necessity of appropriate contrast agent and basic principles of perfusion analysis. The dynamic behavior of contrast agent vascular distribution can be described by arterial input function (AIF). The shape of the curves close to the area of interest is affected by dispersion which is called vascular transport function (VTF) due to the distribution of the contrast agent to the region of interest. Finally the tissue residual function describes system behavior of tissue. The practical part of the diploma thesis is aimed at implementation of model curves AIF, VTF and TRF. Furthermore, a simulation program was created for easy manipulation with introduced models moreover the program is used to perform an estimation of perfusion parameters based on nonblind deconvolution. The method is validated on synthetic data and illustrated on clinical data of the renal cell carcinoma patient.
2

Registrace obrazů - aplikace v oftalmologii a ultrasonografii / Image Registration - Application in ophthalmology and ultrasonography

Harabiš, Vratislav January 2014 (has links)
Image registration is widely used in clinical practice. However image registration and its~evaluation is still challenging especially with regards to new possibilities of various modalities. One of these areas is contrast-enhanced ultrasound imaging. The time-dependent image contrast, low signal-to-noise ratio and specific speckle pattern make preprocessing and image registration difficult. In this thesis a method for registration of images in ultrasound contrast-enhanced sequences is proposed. The method is based on automatic fragmentation into image subsequences in which the images with similar characteristics are registered. The new evaluation method based on comparison of perfusion model is proposed. Registration and evaluation method was tested on a flow phantom and real patient data and compared with a standard methods proposed i literature. The second part of this thesis contains examples of application of image registration in~ophthalmology and proposition for its improvement. In this area the image registration methods are widely used, especially landmark based image registration method. In this thesis methods for landmark detection and its correspondence estimation are proposed.
3

Vliv korekce prostorové rozlišovací schopnosti kolimátoru na kvalitu obrazu v perfuzní scintigrafii myokardu / Effect of resolution recovery on image quality in myocardial perfusion SPECT

Skibová, Daniela January 2013 (has links)
Objectives: Resolution recovery algorithms (IR-RR) were recently proposed as tools to improve quality of SPECT images through better resolution. The aim of the presented study was to investigate the effect of IR-RR on myocardial perfusion SPECT studies. Methods: Phantom and clinical studies were performed using SPECT-CT Infinia/Hawkeye (GE Healthcare). NEMA triple line phantom was scanned according to NEMA procedures. Cold sphere and cardiac phantom were scanned under clinical conditions (900 -angled detectors, 60 views and circular orbit) and reconstructed via IR-RR (Evolution for Cardiac, GE, 12 iterations and 10 subsets), OSEM (ordered subset expectation maximization, 2 iterations and 10 subsets) and FBP (filtered back projection). IR-RR and OSEM reconstructions were used with/without attenuation and scatter correction (ACSC). The effect of post-reconstruction filtering was evaluated. In clinical studies two data-sets were used (half-time and full-time). Conventional scan using full-time (20 sec per stress projection and 25 sec per rest projection) was reconstructed via FBP and IR-RR; half-time scan (10 sec stress, 12 sec rest studies) was reconstructed via IR-RR. End-diastolic volume (EDV), end-systolic volume (ESV) and left ventricular ejection fraction (EF) were calculated using two software...
4

Perfuzní modelování v optické koherentní tomografii / Perfusion Modelling in Optical Coherence Tomography

Štohanzlová, Petra January 2018 (has links)
This thesis deals mainly with perfusion modeling in optical coherence tomography (OCT). The introductory part deals with basic theory of the OCT, including a description of its basic applications. Part of the work was the testing of selected contrasting materials suitable for the OCT and the design and implementation of phantoms, which were subsequently used in the main part of the thesis. In the practical part, attention is paid to the perfusion analysis in the OCT, first the application of the dilution theory in the OCT for flow estimation, then a study testing the basic theory of perfusion on OCT by means of tissue phantom. Another part of the thesis is devoted to the method of speckle variance analysis for flow visualization.
5

Hydratace biokolidů - kalorimetrická studie / Hydration of biocolloids - calorimetric study

Šméralová, Ester January 2019 (has links)
Presented master's thesis focuses on the study of hydration of selected biocolloid substances, specifically humic substances (humic acids and fulvic acids), hyaluronic acid with three different molecular weight, chitosan and dextran. Interaction of biocolloids with water was studied by different methods. The effect of solubility, structure, functional groups in molecule on sorption and hydration ability of these biocolloids was investigated. In the case of hyaluronan the influence of molecular weight was also study. Differential scanning calorimetry DSC and perfusion calorimetry give results of heat of hydration, enthalpies and temperature of crystallization and melting. Thermogravimetric analysis TGA was used to determine the original moisture content of the samples.
6

Využití dekonvoluce v perfuzním zobrazování / Deconvolution in perfusion imaging

Líbal, Marek January 2009 (has links)
The purpose of this study is to introduce the methods of the deconvolution and to programme some of them. For the simulation, the tissue homogeneity model and the model of arterial input fiction were used. These models were engaged as the test procedures with the aim of verify the functionality and utility of the Wiener filter, the Lucy-Richardson algorithm and the Singular value decomposition.
7

Fixace biologických vzorků / Fixation of the biological samples

Brachtl, Martin January 2015 (has links)
The aim of thesis is acquaint with possibilities of fixation biological tissues. Choose a suitable tissue and fix it with formaldehyde and another fixator. Last but not least make measurements which determine effects of formaldehyde on the relaxation time of biological tissues. Mice brains were chosen as a suitable for tissues fixation. Measuring effects of formaldehyde and another fixator to relaxation time carried out at the Institute of Scientific Instuments Academy of Sciences of the Czech Republic.
8

Dávkové zpracování perfusometrických MRI dat / Batch processing of perfusometric MRI data

Filipová, Petra January 2016 (has links)
This diploma thesis deals with the DCE – MRI method (Dynamic contrast enhanced magnetic resonance imaging). Basic principle of magnetic resonance and pulse sequence is described. The diploma thesis focuses on the DCE method, especially on the description of the processing procedure by this method. Description of selected pharmacokinetic models is the part of this diploma thesis as well. Furthermore, description and realization of batch processing by PerfLab system is presented. For verifying purposes of the batch processing functionality real data were measured using created acquisition protocol, which is also part of the diploma thesis.
9

Biomechanické aspekty dynamiky intrakraniálního tlaku při kraniocerebrálním poranění. / Biomechanical aspects of the dynamics of intracranial pressure in traumatic brain injury

Mayer, Martin January 2014 (has links)
Title: Biomechanical aspects of the dynamics of intracranial pressure in traumatic brain injury Author: Ing. Martin Mayer e-mail: mayercz@seznam.cz Department: Department of Anatomy and Biomechanics Supervisor: doc. PaedDr. Karel Jelen, CSc. This PhD thesis "Biomechanical aspects of the dynamics of intracranial pressure in traumatic brain injury" is about the dynamics of intracranial pressure, particularly in relation to the external mechanical action of the patient. Severe head injury is the leading cause of death in patients under 35 years of age. Despite constantly-improving medical and nursing care only one third of patients, after recovery, regained the ability to live independently in the long term. Two-thirds of patients were severely disabled or died. The lifetime cost of such a patient who was not completely cured has been calculated to be $4,000,000. A significant consequence of craniocerebral injuries are secondary brain lesions, which among other means the rise in intracranial pressure (ICP), which can further exacerbate due to intracerebral or extracerebral causes. Therefore, the objective of the treatment is minimizing secondary injury, optimally at the phase of the primary lesion. However, realization of this requirement, about which we can say that is a conditio sine qua non, sometimes leads...
10

Fantomový přípravek pro perfusní zobrazování / Phantom model for perfusion imaging

Borovičková, Michaela January 2012 (has links)
This work focuses on issues relating to the perfusion analysis. The aim of this work is to perform experimental measurements of the phantom and then evaluate the perfusion curves. This curves are used to himation of perfusion hemodynamic parameters, which indicates important informatik about monitoring area. All processes associated with the designation and evaluation are performed in a program named Matlab. The output of work is a system that provides the reader into the problem of perfusion analysis and allows him to understand and know what is the meaning od analysis, what demands are placed on the evaluation and what is the result of this perfusion analysis.

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