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Dissertations / Theses on the topic 'Diagnostika stroje'
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1
Kříž, Petr. "Online vibrační diagnostika vřetene frézovacího stroje DATRON." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402508.
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This master’s thesis deals with online vibration diagnostics of the milling machine spindle. It is aimed at the implementation of the complex online vibration diagnostics system to chosen milling machine, the suggestion of the vibration measurement system and the suggestion of the evaluation of changes of the technical condition of this milling machine spindle. The description of the vibration diagnostics, the description of the milling machine spindle construction and function and the suggestions for the practical application of vibration diagnostics are also parts of this thesis.
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Bowyer, Matouš. "Multiparametrická diagnostika vysokootáčkového stroje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402507.
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The goal of the thesis was applying multiparametric diagnostics to determine the state and wear of a high-speed milling machine. In the theoretical section, selected areas of multiparametric diagnostics have been described as well as a significant focus on vibrodiagnostics. The chosen methods for the practical section were incorporated into the group “metrological diagnostics”. Several different types of measurements have been performed on the designed test piece. The measurements were analyzed and lead to these specific results: a drawing of the test piece, a structured methodology for evaluating the test piece, recommendations for diagnostics of the specific machine, and proposals for the future development of the field of metrological diagnostics.
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Kapusta, Juraj. "Diagnostika stroje založena na modelech." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442841.
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The main idea is focused on the diagnostics of a specific hydraulic system, i.e. sensing the physical quantities of the hydraulic circuit with a tank and a centrifugal pump driven by an asynchronous motor. It is a system of pipes connected to the pump, where due to its work it creates a water flow and a pressure increase. In practice, this issue is also addressed in the energy and nuclear industries. Primary circuits in some cases cannot be designed or modified to be able measure locally the pressure value. It is necessary to measure this quantity indirectly - from the motor currents. The main idea of the work is to diagnose the system by an indirect method - specifically to detect the state of the hydraulic circuit (pressure, flow) from the values that we are able to measure and detect damage in advance. In the second part of the thesis is the application of the parts of a specific hydraulic system in the simulation environment MATLAB Simulink. The model of the hydraulic circuit contains mathematical-physical relations that simulate the course of the mentioned experiment. The results of the simulation are compared with the results of the experiment. The model also investigates the simulation of a fault condition, when we supply pressure pulsations to the hydraulic circuit. It is these changes in the hydraulic part that affect the characteristics of the pump and the asynchronous motor, so we are able to diagnose this system.
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Škrobánek, Martin. "Diagnostický systém papírenského stroje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417858.
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This master thesis deals with the technical diagnostics, focusing mainly on vibration diagnostics. This problematice is described in the first part of this work on a theoretical level. The next part describes the paper machine, diagnostic system and the measuring points are classified into databases. The practical part of this work consists of a proposal for the methodology of vibration diagnostics for a paper machine, the procedure for measuring and evaluating the measured values. Part of the work is also a practical example of the measurement of the central cylinder, on which the procedure is tested, and the compilation of new limit values.
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Rázgová, Benedikta. "Online diagnostika obráběcího stroje MCV 754." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417766.
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This master’s thesis deals with online diagnostics of the machine tool and marginal analysis of surface texture. The first part of the thesis deals with problems theoretically, there are described the machine tools, maintenance, methods of technical diagnostics, specifically online vibrodiagnostic systems and an overview of profile and area parameters. In the practical part, two test samples created under ideal and degraded conditions. In the practical part, two signal processing processes under ideal and degraded conditions are compared using signal analysis from an online vibrodiagnostic system and surface texture analysis. Part of the work is the evaluation of the performed analyzes and recommendations for practice.
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Hrbáček, Vlastimil. "Návrh provozních mezí pro diagnostický systém obráběcího stroje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417438.
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The Master's thesis deals with online vibration diagnostics of a milling center. It contains a methodology to determine the vibration operating limits and to detect machine of condition monitoring. The thesis also contains a general description of maintenance and technical diagnostics with a focus on vibrodiagnostics. The main part of the thesis is to solve the problem of determining the operating limits of spindle vibration depending on the production program. The essence of the solution is to determine vibration limits for individual milling tools.
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Soukup, Patrik. "Diagnostika točivých elektrických strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377107.
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The thesis Diagnostics of rotating electric machines deals with the theory of diagnostics of rotating machines, focusing especially on the diagnosis of asynchronous motors of high power. Due to the importance of maintaining the trouble-free condition of these machines with regard to serviceability, the importance of their diagnosis is growing. Due to inappropriate working conditions or for many other reasons, different types of malfunctions may occur in the machine. The list and the way of occurrence of possible failures are included and explained in this thesis. With the growing age of the machine, it is important to check the insulation status through insulation testing. These tests are performed in the practical part of the thesis and the results are presented. In the case of asynchronous machines, each anomaly leaves a signature in the form of an electrical, magnetic or vibrational signal. These signals are analyzed and evaluated using a specific measuring equipment with the intention of deciding on the current state of the machine. Motor current signature analysis (MCSA) is considered to be the main diagnostic method of asynchronous machines in this thesis. This method is described in detail in this paper and is being applied in electrical engineering.
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Kohutek, Tomáš. "Diagnostika vibrací strojů při kusových zkouškách." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318531.
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This master thesis deals with the vibration diagnostics of machine vibrations during unit tests in industrial company Siemens Electric Machines s.r.o Drásov. In the master thesis is elaborated a design of the diagnostic system which contains selected methods of vibration diagnostics, methology, procedure of measurement and evaluation of measured values. The part of master thesis is also a practical example of measurement on which the mentioned system is tested.
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Rotnágl, Pavel. "Bezpečnost technických syst¨¦mů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228674.
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This thesis is focused on technical systems and evaluating their safety. It tries to make a complex view of links between safety, demands for quality and technical diagnostics. It tries to apply all the information about mentioned features to concrete branch of machines ¨C highŠ\voltage electrical rotary machines. Practical part of this thesis consists of statistical analysis of measured parameters by two hydroelectric generators. Main task of this thesis is to transpose theoretical knowledge of safety and technical systems to the branch of highŠ\voltage electrical rotary machines. This thesis also tries to find appropriate and more efficient evaluation method for analyzing the parameters of mentioned machines. Another benefit of this thesis should be bringing few new ideas about evaluating safety and technical status of highŠ\voltage electrical rotary machines. Keywords: technical system, safety, highŠ\voltage electrical machines, technical diagnostics
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Zářecký, Tomáš. "Online diagnostika obráběcích strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417767.
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This thesis deals with vibration diagnostics and on-line monitoring systems of several producers. Furthermore, this thesis contains a description and evaluation of measuring the vibrations of the machine tool spindle when machining test samples with different cutting conditions and evaluating the surface quality of test samples.
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Svoboda, Miroslav. "Měření a analýza vibrací na částech obráběcích strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241880.
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The aim of the Master‘s Thesis is the measurement and analysis of vibrations on the machine tool parts using a vibration sensor. This work also contains an overview of the current knowledge regarding the issue of the vibrations and the vibration diagnostics, measurement itself and analysis of the measured vibrations.
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Gajdoš, Petr. "Akustická diagnostika strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230417.
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The aim of this master´s thesis is to work out a comparison and evaluation of selected methods used for sound field mapping. Thesis will include software tools and results of sample measurement on test object for each mapping method.
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Hlaváček, Tomáš. "Diagnostika vibrací elektrických strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221311.
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Master’s thesis deals with the influence simulated unbalance vibration level asynchronous motor. First is focused introduction to the problem of vibration. Another part is introduction with machine construction and vibrations in machines. Introduction with methods of measurement. The last part is vibration measurements with simulated imbalances.
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Lexa, Jakub. "Diagnostika vibrací elektrických strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242139.
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This thesis deals with vibration diagnostics of electrical machines. The thesis describes vibrations and their measurement. The next section concernes the diffrent modes of elctrical machines. Vibration of machines are divided into electrical causes and mechanical causes. Practical part deals with the measurement of vibration on the machines and their subsequent analysis. The result of the practical part is determining the fault of the measured induction motors.
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Závorka, Dalibor. "Využití akustické emise při sledování hydraulických strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318403.
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The goal of this diploma thesis is to clarify possibilities of usage of acoustic emission as a hydraulic machinery diagnostics tool. Especially for exposing presence of ruptures or cracks in the parts of machine, assuming changes in acoustic exposure of the part during operation. This clarification is based on series of simple measured experiments, which consist of monitoring the bolt placed in fluid stream inside of a pipe. This bolt was preloaded against inner wall of pipe by appropriate tightening torque. This preload is supposed to simulate effects of the size of rupture. High preload simulates small rupture or none in object and respectively small preload is supposed to simulate big rupture. A group of pressure sensors and accelerometers measures experiments and their evaluations are processed by script created in software MATLAB. Outputs of this script are charts with effective values of respective sensors from the entire record split into individual frequency spectrums. These charts compare spectrums of each configuration to judge effects of parameters changes.
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Čech, Roman. "Diagnostika poruch elektrických strojů pomocí vibrací." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-241129.
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The task of this thesis is to introduce the problems of vibrafon sources in asynchronous motor and their effects and risks to the engine. We will classify the sources of vibration, we will focus for the defects of bearings and for dynamic and static eccentricity. The thesis includes vibration measurement for asynchronous motor, analysis and evaluation of bearings defects and eccentricities.
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Pavlík, Josef. "Vybrané problémy s diagnostiky izolačních systémů točivých elektrických strojů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233987.
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This dissertation thesis deals with the measurement of insulation resistance for rotating electrical machines and polarization indices calculated from them. The first part contains a short theoretical introduction, methods of measurement and basic formulas for calculations. The second part discusses the results obtained in laboratory measurements in both the model and the real coil of high voltage machine. There are also elucidated some of the principles and causes of some phenomena with which the measurement of insulation resistance is encountered. The third part deals with the results of measurements on real machines. There are mainly discussed the dependences of insulation resistance and polarization index on the influences that occur in measurements such as temperature measured insulation, moisture in the insulation, but also the influence of measuring instruments on the measured values. It is also expressed how much these factors affect the measurement results. In addition, this part deals with some other influences that have a negative affect on the measurement of insulation resistance. There is processed a new methodology for measuring insulation resistence in the fourth part of this thesis. The need to develop a metodology of measuring is based on the needs of engineering practice, where is considerable inconsistency of measurement in the present time. Measurement, and often performed on the same machine, are not nowadays often comparable, because measurements are not met even the basic rules resulting from the findings of research and development, which were discovered in the last few decades. Measurement of insulation resistance in our nowdays methodology stagnated on the level of the seventies of 20th century. For this reason, we have developed a new methodology of measurement that takes into account all significant influences affecting the measurement. The purpose of the methodology is to ensure full repeatability and comparability of measurements not only on the same machine but on machines of the same type, in optimal cases, the machines of different types. There are the chapters "The objectives of the work" and "Conclusion" the part of the work. A very important chapter is "The contribution of thesis", which summarizes the original results of this work and results, the use of which is expected in engineering practice.
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Kasalová, Aneta. "Proaktivní systém údržby strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241934.
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This diploma thesis deals with the maintenance and diagnostic failure conditions for machine tools. It is focused on the selection of appropriate methods of technical diagnostic state for machine tools in company SMC Vyškov. As part of the system design and proactive maintenance measurement methodology machine tools.
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Pařík, Zdeněk. "Měření a analýza vibrací systémem OCTAVIS." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229805.
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This thesis is focus at diagnostics of processing machines by diagnostics of vibration with the OCTAVIS system. There is mentioned a view of the present vibration monitoring methods, description of developed diagnosis bench, measuring in this bench and measuring of the chosen production machine.
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Semotam, Petr. "Prediktivní systém údržby obráběcích strojů s využitím vibrodiagnostiky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-382193.
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This diploma thesis concerns issues of predictive and condition based maintenance system of machine tools with using a vibrodiagnostics. It studies and researches its impacts through the basic processes of the maintenance system and characterizes the vibration diagnosis as its tool and mean. There is also described a process of putting condition based maintenance into practice in the practical part of the thesis. The development is realized at Siemens Ltd. Brno with all its requirements and aspects such as a maintenance audit which means the decision on the suitability of condition based maintenance within the current maintenance system, technical analysis as a part of introduction of vibration diagnosis and the practical example of acquiring, recording and assessment of measured vibration. Prior to the end the economic evaluation of the planned predictive maintenance system and the design of the general model of development and implementation of the maintenance system into practice are included.
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Houška, Jan. "Údržba a diagnostika obráběcích strojů se zaměřením na vibrodiagnostiku, elektrodiagnostiku a tribodiagnostiku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378011.
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Master‘s thesis deals with maintenance and related technical diagnostics of machine tools. Diagnostics methods on which is the thesis focused are vibrodiagnostics, tribodiagnostics and electrodiagnostics. Work includes design of diagnostic system and measurement of vibration and electrical parameters of the machining center. Based on given results from data evaluation, further steps in predictive maintenance and usage of technical diagnostics for machine tools are recommended. Within tribotechnical diagnostics, the thesis is based on evaluation of long-term monitoring of process liquid status, which was used in several machining machines. A procedure for the measurement of selected parameters is proposed and periodical liquid status checks are established.
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Jackson, Daniel Lee. "Diagnostic technologies for stroke related events : an economic evaluation." Thesis, University of Surrey, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.576120.
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Abstract Stroke is a very serious medical condition, taking place when there is an interruption in the blood supply to the brain. A related condition, the transient ischaemic attack {TIA}, occurs when the brain's blood supply is temporarily interrupted, and a short episode of neurological dysfunction is experienced by the patient. Understanding the impact of Stroke and TIA on healthcare provision is important. One publication presented here reports a prospective telephone survey undertaken on healthcare providers in Europe and the United States of America, examining the current diagnosis and management of TIA patients. We identified similarities in practice patterns for TIA across countries, although there were variations, such as the patient's point of entry to care and their subsequent follow up. I also review the literature published {since 2000} to determine any trends seen in the incidence, prevalence and mortality associated with Stroke in Europe and the United States. This publication found that Stroke is still a very large public health burden, although there is a continued trend of decreasing Stroke mortality. Economic modelling was undertaken to assess the relative cost effectiveness of diagnostic techniques in rapidly identifying the appropriate patients for post-TIA care in the United Kingdom. This paper presents a deterministic 1 year economic model, and suggests that an alternative pathway of care incorporating rapid access to diagnostic technologies for TIA patient assessment realised cost savings when compared to a modelled current standard of care. Three papers presented here examine the relative cost effectiveness of employing additional diagnostic techniques to facilitate the rapid diagnosis, and subsequent appropriate treatment of acute Ischaemic Stroke patients, through the use of decision analytic techniques. I examine the relative cost effectiveness of the use of an additional MRI technique to identify ischemic stroke patients suitable for treatment in the United States, the cost-effectiveness of employing an additional CT perfusion imaging step to assess these patients, and finally I assess the relative cost-effectiveness of using either an additional MRI or an additional CT based selection technique within the context of the NHS in the UK. The findings from these papers suggest that if diagnostic equipment and facilities exist, then when employed within an appropriate clinical care pathway, their application in Stroke and TIA diagnosis and treatment can be considered to be one of their potentially cost effective uses. 2
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Schmid, Jochen [Verfasser], and O. [Akademischer Betreuer] Dössel. "Microwave Imaging for Stroke Diagnostics / Jochen Schmid ; Betreuer: O. Dössel." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1121683525/34.
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Zolgharni, Massoud. "Magnetic induction tomography for imaging cerebral stroke." Thesis, Swansea University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678669.
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Hübková, Ivana. "Uplatnění diagnostických metod na zařízeních paroplynového bloku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-219905.
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This master´s thesis deals with problem of reliability of technical device in general a so there is explained bathtub curve, defects and malfunctions of devices and then there is a brief outline of reliability system. This thesis further briefly describes technical diagnostic and then there is performed the vibrodiagnostic measurements of selected pumps and ventilators in in heating plant Červený mlýn in Brno. Evaluation of their condition is done according to relevant standards. Further there was done a diagnostic of the steam traps through the ultrasound diagnostic. The last part of my thesis deals with the reliability of selected specific pumps in foregoing rating plant. There are showed reliability curves of selected pumps and elaboration of data from their long-term vibrations measurement.
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Edgar, Deborah Rankine. "A multiple sensor dual chamber waveform recording diagnostic pacemaker." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363426.
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Brazzelli, Miriam. "Studies to inform the methods for Cochrane systematic reviews of diagnostic accuracy in stroke medicine." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5566.
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Background A variety of tests are used in clinical practice to help the diagnostic process and so improve patient care. Many aspects of stroke management depend on accurate and rapid diagnosis. Brain imaging, including CT or MRI, is necessary to identify the location and extent of the cerebral lesion, and to determine the pathological type of stroke and its likely cause. Current treatments - such as thrombolysis - for ischaemic stroke have increased the need for clear evidence on which imaging test is optimal for diagnosis in the acute phase of stroke. Systematic reviews of diagnostic test accuracy may provide evidence on the best use of a diagnostic test in clinical practice and help clinicians to decide among alternative tests. The Cochrane Collaboration has recently included systematic reviews of diagnostic test accuracy within its remit. However, to prepare Cochrane systematic reviews of diagnostic test accuracy is challenging because the methods for such reviews are still in a state of flux. Materials and methods The research work undertaken for this thesis addresses four relevant methodological aspects of such reviews and, I hope, will contribute to informing the development of the methods for Cochrane systematic reviews of test accuracy: i) I assessed the quality of reporting of imaging studies in stroke medicine published between 1995 and 2008 with the current STAndards for the Reporting of Diagnostic accuracy studies (STARD) criteria; ii) I assessed the magnitude of publication bias in diagnostic accuracy studies in stroke medicine, by reviewing all diagnostic abstracts presented at two international stroke meetings between 1995 and 2004 and so evaluating the characteristics and findings of the identified abstracts; iii) I have evaluated the methods for preparing reviews of test accuracy by undertaking a pilot review according to the draft recommendations of the Cochrane Diagnostic Test Accuracy Working Group; iv) I conducted a survey to assess a) how well clinicians and health professionals interpret findings of Cochrane systematic reviews of diagnostic accuracy presented in summary documents; and b) what is the best format for summarising findings of Cochrane reviews of diagnostic accuracy. Conclusions In conclusion, methodological issues concerning the validity and reliability of findings of studies included in systematic reviews of diagnostic accuracy remain of fundamental importance. More empirical evidence is needed to address potential biases such as reporting bias and publication bias. To allow dissemination of diagnostic reviews findings in clinical practice better ways of communicating main characteristics and key results of systematic reviews of diagnostic accuracy should be considered. In the current literature, the quality of reporting and methodological quality of imaging studies for the diagnosis of stroke is less than satisfactory and leaves room for improvement. This is worrying, especially if current health imaging policies are in fact based on poor quality evidence and hence scarce health resources may not being deployed as effectively as they could be.
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Lovelock, Caroline. "The clinical epidemiology of haemorrhagic stroke : time trends and diagnostic tissues." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497042.
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Fattori, Alves Allan Felipe. "Image Processing for Enhancement of Ischemic Stroke in Computed Tomography Examinations." Thesis, Orléans, 2019. http://www.theses.fr/2019ORLE2003.
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L’Accident Vasculaire Cérébral (AVC) est l'une des principales causes de décès dans le monde. Le scanner et l'Imagerie par Résonance Magnétique (IRM) sont les deux principales techniques d'imagerie utilisées pour détecter les AVC. L’examen par scanner reste donc la principale méthode de diagnostic. Dans la plupart des cas, l'évaluation de la région cérébrale compromise est effectuée de manière subjective et peut entraîner des difficultés pour déterminer la région atteinte. Ce travail de thèse propose une approche basée sur un algorithme permettant de mettre en évidence les régions atteintes d’AVC ischémique dans les examens de scanner rétrospectifs. Différentes méthodes de traitement des images ont été utilisées pour réhausser les régions des tissus ischémiques. Afin de permettre aux médecins moins expérimentés de détecter de manière fiable les signes précoces AVC, une nouvelle approche est proposée pour améliorer la perception visuelle de l’accident ischémique cérébral. Une série de 41 images scanner rétrospectifs ont été utilisées, réparties en 25 cas d’AVC ischémiques et 16 patients normaux. Les cas d'AVC ont été obtenus dans les 4,5 heures suivant l'apparition des symptômes. Après la sélection des coupes importantes, une moyenne d'image est effectuée pour réduire le bruit. Ensuite, un modèle de décomposition variationnelle est appliqué afin de conserver la composante pertinente de l'image. Enfin, un algorithme d’espérance-maximisation est appliqué. Un test est proposé afin d’évaluer la performance des observateurs dans un environnement clinique avec et sans l'aide d'images rehaussées. La sensibilité globale de l'analyse de l'observateur a été améliorée de 64,5% à 89,6% et la spécificité de 83,3% à 91,7%. Ces résultats montrent l'importance d'un outil informatique d'aide à la décision en neuroradiologie, notamment dans les situations critiques telles que le diagnostic d'accident ischémique cérébralStroke is one of the highest causes of death worldwide. Non-enhanced computed tomography (CT) and nuclear magnetic resonance imaging (MRI) are the two main imaging techniques used to detect stroke. CT has a lower cost and greater accessibility of the population, so it is still the main method used. In most cases, the assessment of the compromised brain area is performed subjectively and may lead to difficulties in diagnosis. This research proposes an approach based on a computational algorithm, highlighting regions of ischemic stroke. Different image processing methods were used to enhance ischemic tissues. A set of 41 retrospective CT scans from Botucatu Medical School (Brazil) was used, divided into 25 cases of acute ischemic stroke and 16 normal patients. Stroke cases were obtained within 4.5 h of symptom onset. After selection of CT slices, image averaging was performed to reduce the noise. This was followed by a variational decomposition model and the expectation maximization method was applied to generate enhanced images. We determined a test to evaluate the performance of observers in a clinical environment with and without the aid of enhanced images. The overall sensitivity of the observer’s analysis was 64.5 % and increased to 89.6 % and specificity was 83.3 % and increased to 91.7 %. These results show the importance of a computational tool to assist neuroradiology decisions, especially in critical situations such as the diagnosis of ischemic stroke
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Sahlin, Carin. "Sleep apnea and sleep : diagnostic aspects." Doctoral thesis, Umeå : Umeå universitet, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-18959.
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Schieferdecker, Nicola [Verfasser], and Martin [Akademischer Betreuer] Dichgans. "Platelet-associated miRNAs as potential diagnostic biomarkers after acute ischemic stroke / Nicola Schieferdecker ; Betreuer: Martin Dichgans." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://nbn-resolving.de/urn:nbn:de:bvb:19-281797.
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Warburton, Elizabeth. "Mechanisms for the recovery of aphasia following stroke : a positron emission tomography study." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299261.
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Essack, Magbubah. "Transcription Regulation and Candidate Diagnostic Markers of Esophageal Cancer." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5306_1267148426.
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This thesis reports on the development of a novel comprehensive database (Dragon Database of Genes Implicated in Esophageal Cancer, DDEC) as an integrated knowledge database aimed at representing a gateway to esophageal cancer related data. More importantly, it illustrates how the biocurated genes in the database may represent a reliable starting point for divulging transcriptional regulation, diagnostic markers and the biology related to esophageal cancer.
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Osborne, Jesse. "A Protocol Driven Stroke Code's Impact on Door-to-Needle Times." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etd/3754.
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Tissue plasminogen activator (tPA) is most effective the faster it is able to be administered to a patient that has been affected by stroke. A Stroke Code is a strategy that acute care facilities implement to reduce the time from diagnosing a stroke to administering tPA. The purpose of this study was to determine if the initiation of a Stroke Code in an acute care hospital reduces the door-to-needle time for patients affected by a stroke. In particular, does a Stroke Code reduce door-to-needle times. The research was conducted using data from April 1, 2014 to December 31, 2014 (pre-Stroke Code period) and September 1, 2015 to December 31, 2016 (post-Stroke Code period). The population of this study was treated at Holston Valley Medical Center in Kingsport, Tennessee. The analysis revealed a decrease in door-to-needle times after a Stroke Code was implemented at the acute care facility.
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Fordell, Helena. "Virtual Reality for Enriched Rehabilitation of Stroke Patients with Spatial Neglect : Diagnostics and the Rehabilitation Effect on Spatial Attention and Neuronal Activity." Doctoral thesis, Umeå universitet, Institutionen för farmakologi och klinisk neurovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-141920.
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Background: Approximately a third of all stroke patients develop spatial neglect, a debilitating symptom associated with poor outcome. Spatial neglect is clinically defined as a deficit in processing and responding to stimuli presented on the contralesional side of the body, or the space surrounding that side of the body. The heterogenetic, multi-sensory nature of the symptoms renders it difficult to diagnose and treat; therefor effective methods for screening and intervention for neglect are needed. Virtual reality (VR) is a method of brain–computer interaction that involves realtime simulation of an environment, scenario or activity that allows for user interaction and targets multiple senses. We hypothesize that VR can facilitate identification of spatial neglect in stroke patients and that training with this interface will improve patient’s functional outcome, through stimulation to neuronal networks including those controlling attention. Objective: The objective was to construct and validate a computerized test battery for spatial neglect and to investigate its usability in stroke patients. Also to design and develop a VR rehabilitation method for spatial neglect and to evaluate its effects on spatial attention and on neuronal activity in the brain. Method: We designed, developed and evaluated a new concept for assessment (VR-DiSTRO®) and training (RehAtt®) of spatial attention, using VR technology. The hardware consisted of a PC, monitor, 3D-glasses and a force feedback device to control the tasks (i.e., a robotic pen). The software enabled targets to be moved, rotated and manipulated in the 3D environment using the robotic pen. RehAtt® made it possible to combine intense visual scanning training, multi-sensory stimulation (i.e., audio, visual, tactile) and sensory-motor activation of the contralesional arm. In a first study on 31 stroke patients we performed a construct validation of VR-DiSTRO® against Rivermead Behavioural Test Battery (BIT) and investigated the usability. In a second study, 15 subjects with chronic spatial neglect (symptoms >6 month) had self-training, 3 x 1 hour for 5 weeks using RehAtt®. Outcome were measured by changes in neglect tests and in Cathrine Bergego Scale (CBS). Training-related changes in neuronal activity of the brain was studied using fMRI during task and in resting state. Results: VR-DiSTRO® correctly identified all patients with neglect. The sensitivity was 100% and the specificity 82% for VR-DiSTRO® compared to BIT. Usability was high and no side-effects were noted. Using repeated measurement analysis, improvements due to the RehAtt® intervention were found for Baking tray task (p < 0.001), Star cancellation test (p = 0.006) and Extinction test (p = 0.05). Improvements were also seen in the Posner task as fewer missed targets (p = 0.024). Improvement in activities of daily living (CBS) was shown immediately after training (p < 0.01) and patients still reported improvement at 6 months follow-up. Trainingrelated changes in neuronal activity were seen as an increased task-evoked brain activity in prefrontal and temporal cortex, mainly outside the attention network but in related cortical areas. During resting state, changes in network connectivity were seen after intervention with RehAtt® in the Dorsal Attention Network (DAN) and interhemispheric connectivity. Conclusion: VR-DiSTRO® identified visuospatial neglect in stroke patients quickly and with a high accuracy. RehAtt® training improved in spatial attention in chronic neglect with transfer to functions in daily living. Increased neuronal brain activity was found in and between attention networks and related brain structures. This could represent a compensatory effect in addition to sign of a restorative effect from the RehAtt training. The results obtained in this study are promising, encourage further development of the methods and merit for further studies.
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Brand, Jannik [Verfasser]. "Präklinische Diagnostik und Therapie in einer Mobilen Stroke Unit zur Verkürzung der Zeit bis zur intravenösen Thrombolyse beim akuten ischämischen Schlaganfall / Jannik Brand." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1219507865/34.
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El, Hajj Maya. "Elaboration d'un Score Prédictif des Accidents Vasculaires Cérébraux au Liban." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC0078/document.
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Background : L’accident Vasculaire Cérébral (AVC) est la deuxième cause de décès au Liban et dans le monde. Il existe une pénurie d'informations fiables concernant l'épidémiologie de l'AVC au Liban. L’objectif de cette étude est d’identifier les facteurs de risque et les symptômes d'AVC dans la population libanaise et de développer un score pour la future prédiction de l'AVC et un score pour le diagnostic de l'AVC en situation d'urgence.Méthodes : Une étude cas-témoin a été menée pour la génération des scores. Les données ont été collectées à l’aide d’une fiche de collecte de données conçue dans deux hôpitaux tertiaires au Liban entre le 1er janvier 2012 et le 31 décembre 2014. Une régression logistique a permis de déterminer les facteurs de risque et les symptômes d'AVC. Les coefficients arrondis ont engendré un score pour le risque d’AVC (ROSS) et un score de diagnostic de l'AVC (DS-Stroke). Une autre étude cas-témoin a été menée pour la validation des scores, où les données ont été collectées à l'aide d'un questionnaire normalisé dans cinq différents hôpitaux tertiaires entre le 1er janvier 2015 et le 31 décembre 2016. Le ROSS et le DS-Stroke ont été validés en les comparant au diagnostic final des hôpitaux.Résultats : En total, 732 participants ont été inclus dans l'étude de génération du score (202 cas d'AVC et 530 contrôles sans AVC) et 650 participants ont été inclus dans l'étude de validation du score (205 cas et 445 contrôles sans AVC). Plusieurs facteurs de risque et symptômes ont été associés à l'AVC au Liban. Le ROSS et le DS-Stroke ont été construits et évalués avec des hautes zones sous la courbe et des valeurs négatives et positives prédictives élevées.Conclusion : Le ROSS est un bon outil d'évaluation des risques pour améliorer la prévision de l'AVC dans la population libanaise et serait particulièrement intéressant dans le cadre des soins primaires afin de réduire l'incidence de l'AVC. Le DS-Stroke est un autre outil précieux à utiliser pour le diagnostic de l'AVC à l'urgence et serait intéressant pour l'utilisateur afin d'avoir un diagnostic précis de l'AVC, appeler à d'autres tests d'urgence si nécessaire et d’accélérer le traitement pour les patients AVCBackground: Stroke is the second leading cause of death in Lebanon and worldwide. There is a scarcity of reliable information about the epidemiology of stroke in Lebanon. We aim to identify stroke risk factors and symptoms in the Lebanese population and develop a score for future stroke prediction and another for stroke diagnosis at emergency.Methods: A case-control study was conducted for the scores generation. Data were collected through a designed data collection sheet at two tertiary hospitals in Lebanon between January 1st, 2012 and December 31st, 2014. A logistic regression determined stroke risk factors and symptoms and the rounded coefficients generated a Risk of Stroke Score (ROSS) and a Diagnosis Score for Stroke (DS-Stroke). Another case-control study was conducted for the scores validation where data were collected through a standardized questionnaire at five different tertiary hospitals between January 1st, 2015 and December 31st, 2016. ROSS and DS-Stroke were validated by comparing them to the hospitals final diagnosis.Results: In total, 732 participants were included in the score generation study (202 stroke cases and 530 stroke-free controls) and 650 participants were included in the score validation study (205 cases and 445 stroke-free controls). Many risk factors and symptoms were found to be associated with stroke in Lebanon. ROSS and DS-Stroke were constructed and validated with high areas under the curve and high negative and positive prediction values.Conclusion: ROSS is a good risk assessment tool for use to improve the prediction of stroke in the Lebanese population and would be of particular interest in the primary care setting to reduce stroke incidence. DS-Stroke is another valuable tool to use for stroke diagnosis at emergency and would be interesting to user in order to have an accurate diagnosis of stroke, call for further emergency testing if necessary and speed up the treatment for stroke patients
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Hingot, Vincent. "Development of ultrasound localization microscopy to measure cerebral perfusion during stroke : a study in mouse models prior to its translation in humans." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS562.
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L’échographie est une technique d’imagerie médicale employant des ultrasons. Un examen classique se base sur deux modes principaux, le mode B pour l’imagerie anatomique et le mode Doppler pour l’imagerie des flux sanguins.Dans le contexte des maladies cérébro-vasculaires, l’échographie sert principalement à estimer les altérations du flux sanguin dans les artères cérébrales majeures au travers du Doppler transcranien. Cependant, la faible qualité des images à travers le crâne ne permet pas à l’échographie d’être aussi performante que l’imagerie par résonance magnétique.Les récents progrès en échographie ont permis l’émergence de nouveaux modes d’imagerie, en particulier une technique de super-résolution ultrasonore qui permet d’augmenter la résolution ainsi que le contraste de l’imagerie vasculaire. Elle se base sur l’imagerie rapide de microbulles couramment utilisées comme agents de contraste pour l’échographie. En utilisant cette méthode, il a été possible d’imager jusqu’aux plus petits vaisseaux et permettrait chez l’homme l’imagerie de la perfusion cérébrale de manière plus performante que le Doppler transcranien. Cela pourrait rendre possible une prise en charge plus précoce et plus efficace des patients victimes d’accidents vasculaires cérébraux. Avant d’être utilisée dans un contexte médical, la technique de super-résolution ultrasonore doit être mieux comprise, mieux réalisée, et adaptée au contexte particulier des accidents vasculaires cérébraux. En particulier, ce manuscrit discutera des meilleures méthodes de formation d’image, et se penchera sur les performances réelles de l’imagerie super résolue. Nous discuterons également des possibilités de corriger les artefacts dus aux mouvements physiologiques et des possibilités d’utiliser l’imagerie super résolue dans divers organes et en particulier les reins, les tumeurs et la moelle épinière. L’étude approfondie par imagerie super résolue de modèles d’ischémie cérébrale chez le rongeur permettra de construire des biomarqueurs vasculaires adaptés au diagnostic des pathologies cérébro-vasculaires et devrait aider la translation vers des patients humainsUltrasonography is a medical imaging technique that uses ultrasound. A typical examination is based on two main modes, B-mode for anatomical imaging and Doppler mode for blood flowimaging. In the context of cerebrovascular diseases, ultrasonography is used primarily to estimate alterations in blood flow in major cerebral arteries through transcranial Doppler. However, the low quality of the images through the skull does not allow ultrasound to be as efficient as magnetic resonance imaging. Recent advances in ultrasound have led to the emergence of new modes of imaging, particularly a super-resolution ultrasound technique that increases the resolution and contrast of vascular imaging. It is based on the rapid imaging of microbubbles commonly used as contrast agents for ultrasound. This method has shown that it can image even the smallest vessels and allows to perform cerebral perfusion imaging more effectively than Transcranial Doppler. This would allow earlier and more effective management of stroke patients. Before being used in a medical context, this ultrasound super-resolution technique must be better understood, better realized, and adapted to the particular context of cerebrovascular diseases. In particular, this manuscript will discuss how to best form images, and will look at the actual performance of super-resolved imaging. We will also discuss the possibilities of correcting artefacts due to physiological movements and the possibilities of using super-resolved imaging in various organs, particularly the kidneys, tumors and spinal cord. Finally, imaging of models of cerebral ischemia in rodents will enable the construction of vascular biomarkers suitable for the diagnosis of cerebrovascular pathologies and should aid translation into human patients
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Chueh, Juyu. "Mechanical Flow Restoration in Acute Ischemic Stroke: A Model System of Cerebrovascular Occlusion: A Dissertation." eScholarship@UMMS, 2010. https://escholarship.umassmed.edu/gsbs_diss/493.
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Stroke is the third most common cause of death and a leading cause of disability in the United States. The existing treatments of acute ischemic stroke (AIS) involve pharmaceutical thrombolytic therapy and/or mechanical thrombectomy. The Food and Drug Administration (FDA)-approved recombinant tissue plasminogen activator (tPA) administration for treatment of stroke is efficacious, but has a short treatment time window and is associated with a risk of symptomatic hemorrhage. Other than tPA, the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) retriever system and the Penumbra Aspiration system are both approved by the FDA for retrieval of thromboemboli in AIS patients. However, the previous clinical studies have shown that the recanalization rate of the MERCI system and the clinical outcome of the Penumbra system are not optimal. To identify the variables which could affect the performance of the thrombectomy devices, much effort has been devoted to evaluate thrombectomy devices in model systems, both in vivo and in vitro, of vascular occlusion. The goal of this study is to establish a physiologically realistic, in vitro model system for the preclinical assessment of mechanical thrombectomy devices.
In this study, the model system of cerebrovascular occlusion was mainly composed of a human vascular replica, an embolus analogue (EA), and a simulated physiologic mock circulation system. The human vascular replica represents the geometry of the internal carotid artery (ICA)/middle cerebral artery (MCA) that is derived from image data in a population of patients. The features of the vasculature were characterized in terms of average curvature (AC), diameter, and length, and were used to determine the representative model. A batch manufacturing was developed to prepare the silicone replica.
The EA is a much neglected component of model systems currently. To address this limitation, extensive mechanical characterization of commonly used EAs was performed. Importantly, the properties of the EAs were compared to specimens extracted from patients. In the preliminary tests of our model system, we selected a bovine EA with stiffness similar to the thrombi retrieved from the atherosclerotic plaques. This EA was used to create an occlusion in the aforesaid replica. The thrombectomy devices tested included the MERCI L5 Retriever, Penumbra system 054, Enterprise stent, and an ultrasound waveguide device. The primary efficacy endpoint was the amount of blood flow restored, and the primary safety endpoint was an analysis of clot fragments generated and their size distribution.
A physiologically realistic model system of cerebrovascular occlusion was successfully built and applied for preclinical evaluation of thrombectomy devices. The recanalization rate of the thrombectomy device was related to the ability of the device to capture the EA during the removal of the device and the geometry of the cerebrovasculature. The risk of the embolic shower was influenced by the mechanical properties of the EA and the design of the thrombectomy device.
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Strobel, Christian Günther [Verfasser], and Martin [Akademischer Betreuer] Fischer. "Watching people fail : fostering diagnostic competences with peer feedback on erroneous cognitive modeling examples / Christian Günther Strobel ; Betreuer: Martin Fischer." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/1160876363/34.
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Pavilla, Aude. "Quantification simultanée de la diffusion et de la perfusion cérébrale en imagerie par résonance magnétique : application au diagnostic de l’accident vasculaire cérébral ischémique." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B025/document.
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L’accident vasculaire cérébral ischémique (AVCi) représente un véritable enjeu de santé publique avec des taux de mortalité et des coûts de prise en charge élevés. L’établissement d’un diagnostic rapide et précis basé sur les signes cliniques et les résultats de l’imagerie médicale est nécessaire pour la prise de décision thérapeutique (thrombolyse ou plus récemment la thrombectomie mécanique). Conformément aux recommandations actuelles, l’IRM est la modalité d’imagerie de première intention à réaliser pour confirmer la suspicion d’AVCi. La réalisation d’une thrombolyse est notamment guidée par l’existence d’une discordance (ou « mismatch ») diffusion-perfusion, déterminée à partir de deux séquences distinctes, associée à un meilleur pronostic pour le patient. La séquence IVIM (« Intravoxel Incoherent Motion») permet l’étude simultanée de la diffusion et de la microcirculation à partir de l’analyse biexponentielle du signal issu d’une unique séquence de diffusion sensibilisée à la perfusion. Par conséquent, cette séquence présente un fort potentiel pour le diagnostic de l’AVCi. Le travail méthodologique de cette thèse a consisté en l’optimisation des acquisitions et des traitements de données pour l’imagerie quantitative simultanée de la diffusion et de la perfusion cérébrale avec la méthode IVIM. Dans un premier temps, le modèle biophysique conventionnel et les acquisitions de la séquence IVIM ont été validés dans le cadre d’une étude sur sujet sain, en comparaison aux mesures de perfusion obtenues avec l’ASL (Arterial Spin Labeling). Dans un deuxième temps, le modèle conventionnel a été modifié pour la prise en compte du comportement non-gaussien de la diffusion dans le parenchyme cérébral à l’aide d’un paramètre quantitatif supplémentaire, le kurtosis (modèle DKI-IVIM). Ce modèle a été validé expérimentalement avec une étude sur sujet sain en comparaison au modèle standard biexponentiel IVIM. Enfin, la méthodologie développée a été mise en œuvre dans un cadre clinique sur cinq patients souffrant d’AVCi. Les résultats préliminaires obtenus démontrent l’efficacité de la méthode DKI-IVIM pour le diagnostic de l’AVCi en phase aigüe, en comparaison avec la méthode conventionnelle diffusion-perfusion ASL avec l’estimation du paramètre supplémentaire du kurtosis permettant une meilleure caractérisation de l’atteinte parenchymateuseIschemic stroke is a serious neurological disease of public health concern that constitutes a major cause of death and high costs of medical care. A quick and accurate diagnosis based on both clinical signs and medical images is necessary for the therapeutic decision (thrombolysis or mechanical thrombectomy). In accordance with the current recommendations, MRI is the primary intention modality to perform in order to confirm the ischemic stroke suspicion. The choice of a thrombolysis treatment is guided by the presence of a diffusion-perfusion mismatch, determined with two different sequences, and is associated with a better life outcome for the patient. The IVIM (« Intravoxel Incoherent Motion ») MRI sequence allows for the simultaneous diffusion and microperfusion quantification with the biexponential analysis of the diffusion signal obtained by a diffusion sequence sensitized to perfusion. This sequence could be of great interest for the ischemic stroke diagnosis. The methodological aspects implemented during this thesis consisted of the optimization of the acquisitions and data processing of IVIM imaging for quantitative assesments of cerebral diffusion and perfusion. First of all, the conventional biophysical model and IVIM sequence acquisitions were implemented and validated with a study on healthy subjects, in comparison with perfusion assesments obtained using ASL (Arterial Spin Labeling). Secondly, the conventional model was modified to consider the non-gaussian diffusion behavior in tissues with an additional quantitative parameter estimation, the kurtosis (DKI-IVIM model). This new model was also validated with a study on healthy subjects in comparison with the standard biexponential IVIM model. Finally, this method was applied in a clinical setting on five stroke patients. The preliminary results demonstrated the DKI-IVIM method efficiency for the acute ischemic stroke diagnosis when compared with the conventional diffusion-ASL perfusion with the additional estimation of the kurtosis for a better lesion characterization
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Pinto, Ferreira Philippe Daniel [Verfasser], and Andrés [Akademischer Betreuer] Kecskeméthy. "Development of Functional Numerical Scores for Improving the Diagnostic of Motion Impairment of Stroke Patients using Non-Traditional Gait Parameters / Philippe Daniel Pinto Ferreira ; Betreuer: Andrés Kecskeméthy." Duisburg, 2017. http://d-nb.info/1132510627/34.
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Msayib, Yunus. "Quantifying impaired metabolism following acute ischaemic stroke using chemical exchange saturation transfer magnetic resonance imaging." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:a98323ce-5998-436d-bca4-09df549cf191.
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In ischaemic stroke a disruption of cerebral blood flow leads to impaired metabolism and the formation of an ischaemic penumbra in which tissue at risk of infarction is sought for clinical intervention. In stroke trials, therapeutic intervention has largely been based on perfusion-weighted measures, but these have not been shown to be good predictors of tissue outcome. The aim of this thesis was to develop analysis techniques for magnetic resonance imaging (MRI) of chemical exchange saturation transfer (CEST) in order to quantify metabolic signals associated with tissue fate in patients with acute ischaemic stroke. This included addressing robustness for clinical application, and developing quantitative tools that allow exploration of the in-vivo complexity. Tissue-level analyses were performed on a dataset of 12 patients who had been admitted to the John Radcliffe Hospital in Oxford with acute ischaemic stroke and recruited into a clinical imaging study. Further characterisation of signals was performed on stroke models and tissue phantoms. A comparative study of CEST analysis techniques established a model-based approach, Bloch-McConnell model analysis, as the most robust for measuring pH-weighted signals in a clinical setting. Repeatability was improved by isolating non-CEST effects which attenuate signals of interest. The Bloch-McConnell model was developed further to explore whether more biologically-precise quantification of CEST effects was both possible and necessary. The additional model complexity, whilst more reflective of tissue biology, diminished contrast that distinguishes tissue fate, implying the biology is more complex than pH alone. The same model complexity could be used reveal signal patterns associated with tissue outcome that were otherwise obscured by competing CEST processes when observed through simpler models. Improved quantification techniques were demonstrated which were sufficiently robust to be used on clinical data, but also provided insight into the different biological processes at work in ischaemic tissue in the early stages of the disease. The complex array of competing processes in pathological tissue has underscored a need for analysis tools adequate for investigating these effects in the context of human imaging. The trends herein identified at the tissue level support the use of quantitative CEST MRI analysis as a clinical metabolic imaging tool in the investigation of ischaemic stroke.
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Miller, Lakisha Chitique. "Medical Resident Turnover and Its Association with Inpatient Mortality in Patient Discharges with a Primary Diagnosis in the Heart Disease, Cancer, or Stroke Diagnostic Groups at U.S. Teaching Hospitals, 2002." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1239044238.
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Brunner, Clément. "Functional ultrasound imaging (fUSi) to assess brain function in physiological and pathological conditions : application to stroke." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB123/document.
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Depuis le milieu du XXème siècle, les techniques d’imagerie fonctionnelles ont un rôle grandissant dans notre compréhension sur les fonctions du cerveau en conditions physiologique et pathologique. Bien que l’IRMf fasse partie des techniques les plus communément utilisées pour l’imagerie du cerveau complet lors d’études préclinique et clinique, cette modalité souffre de sa résolution spatiotemporelle et sa sensibilité pour enregistrer finement les fonctions et activités cérébrales. Récemment l’imagerie fonctionnelle par ultrason (ifUS) a subi des développements permettant d’être complémentaires à l’IRMf ainsi qu’aux autres techniques d’imagerie cérébrales classiquement employées. Contrairement aux ultrasons focalisés conventionnels, l’imagerie hémodynamique proposé par l’ifUS repose sur une illumination ultrasonore plane permettant la détection des globules rouges en mouvement et la mesure de leur vitesse dans les micro-vaisseaux cérébraux. De ce fait, l’ifUS est indirectement lié à l’activité cérébrale d’où l’importance d’une meilleure compréhension des mécanismes du couplage neuro-vasculaire liant l’activité neuronale et les variations cérébrales d’apport en sang. De plus, cette technique a le potentiel pour fournir des informations précises sur les processus de certaines pathologies à la fois sur des modèles précliniques et chez l’homme. Dans un premier temps, j’exposerais mes travaux sur les récents développements techniques permettant l’ifUS in vivo (i) en condition chronique, (ii) sur l’animal éveillé, libre de mouvement et effectuant une tache comportementale et (iii) des vaisseaux capillaires chez le rongeur et l’homme. Dans un second temps, je démontrerais que l’ifUS in vivo peut fournir des informations nouvelles sur des pathologies telles que l’accident vasculaire cérébraleSince the middle of the 20th century, functional imaging technologies are making an increasing impact on our understanding on brain functions in both physiological and pathological conditions. Even if fMRI is nowadays one of the most used tool for whole brain imaging in pre-clinical and clinical studies, it lacks sufficient spatiotemporal resolution and sensitivity to assess fine brain function and activity. Functional ultrasound imaging (fUSi) has been recently developed and presents a potential to complement fMRI and other existing brain imaging modalities. Contrary to conventional ultrasound using focus beams, fUSi relies on hemodynamic imaging based on ultrasound plane-wave illumination to detect red blood cells movement and velocity in brain micro-vessels. Consequently, the fUSi signal is indirectly related to brain activity and it is therefore important to better understand the mechanisms of the neurovascular coupling linking neural activity and cerebral blood changes. Here again, fUSi may provide relevant information about disease processes in preclinical models but also in humans. First, I will present recent technical developments allowing in vivo fUSi (i) in chronic condition, (ii) in freely moving and behaving rats and (iii) in rodents and human brain capillaries. Second, I will demonstrate how fUSi could provide new insights in brain pathologies such as stroke
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Kremer, Maximilian [Verfasser], and Herbert [Akademischer Betreuer] Nägele. "Performance des Medtronic Reveal LINQ (TM) Ereignisrekorders bei der Diagnostik von Herzrhythmusstörungen in Patienten mit transientem Bewusstseinsverlust durch Synkopen unklarer Ätiologie und Patienten mit Embolic Stroke of Undetermined Source / Maximilian Kremer ; Betreuer: Herbert Nägele." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1200100514/34.
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Luvizutto, Gustavo José [UNESP]. "Investigação de negligência espacial unilateral após Acidente Vascular Cerebral." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/139529.
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Introdução: A negligência espacial unilateral (NEU) é caracterizada pela incapacidade de reportar ou responder pessoas ou objetos do lado contralateral à lesão cerebral, e ocorre principalmente após Acidente Vascular Cerebral (AVC) do lobo parietal direito, sendo associada à pior desfecho funcional à longo prazo. Objetivo: Os objetivos desta tese foram: normatizar os principais testes diagnósticos de NEU e verificar a relação com fatores sócio-demográficos na população brasileira; avaliar as variáveis bioquímicas que interferem na NEU na fase aguda do AVC; e revisar sistematicamente os principais tratamentos farmacológicos na NEU em pacientes após AVC. Método: Para o primeiro objetivo foi realizado estudo transversal em 150 indivíduos sem alterações neurológicas, sendo aplicados: teste face-mão (TFM), testes de cancelamento de linhas (TCL), cancelamento de estrelas (TCE) e bisseção de linhas (TBL). Os resultados dos testes foram relacionados com o perfil sócio demográfico da população, sendo estipulado pontos de cortes para a normalidade; para o objetivo 2 foi realizado estudo observacional em 40 indivíduos com diagnostico de NEU após AVC. Foram aplicados os TCL, TCE e TBL, sendo relacionado com o nível de hemoglobina na fase aguda do AVC corrigido para potenciais confundidores; para o objetivo 3 foi realizado revisão sistemática de literatura por meio de ensaios clínicos randomizados e quasi-randomizados para determinar o melhor tratamento farmacológico. Resultados: os resultados do objetivo 1 estão apresentados nos artigos 1 e 2; o objetivo 2 no artigo 3; e o objetivo 3 no artigo 4. Conclusão: Com base nos resultados obtidos dos artigos 1 e 2, o TFM apresenta taxa de normalidade entre 8 a 10 estímulos sensoriais, com prevalência de extinção associada com o grau de escolaridade e aumento da idade; no TCL o ponto de corte para considerar NEU é acima de 0 e no TCE acima de 2, ambos associados à idade. No TBL o ponto médio de corte para considerar NEU foi de 6,6 mm, associado com pior escolaridade. No artigo 3 foi observado que quanto menor o valor de hemoglobina na fase aguda do AVC, pior o desempenho nos testes de NEU; No artigo 4 foi observado que a efetividade e segurança dos tratamentos farmacológicos para NEU após AVC permanecem incertos, necessitando de ensaios clínicos randomizados adicionais para avaliar o efeito deste tratamento.
Background: Unilateral spatial neglect (USN) is characterized by the inability to report or respond to people or objects presented on the side contralateral to the lesioned side of the brain and has been associated with poor functional outcomes. Objective: The objectives of this thesis were: to standardize the USN tests and verify the relationship with socio-demographic data in the Brazilian population; evaluate the biochemical variables that influence in USN tests after acute stroke; and systematically review the pharmacological interventions to treat USN after stroke. Method: For the first aim, we performed a cross-sectional study of 150 individuals without neurological changes by applying: face-hand test (FHT), line cancellation test (LCT), star cancellation test (SCT) and line bisection test (LBT). The test results were related to the sociodemographic data, with cutoff points being stipulated to define USN; the second aim was achieved by conducting an observational study of 40 individuals with USN after acute stroke. The tests applied – LCT, SCT and LBT – were correlated with the hemoglobin level in the acute phase of stroke corrected by confounders; the third aim was analyzed by a systematic review of randomized controlled trials and quasi-randomized clinical trials to determine the efficacy of pharmacological intervention. Results: The first aim is presented in Articles 1 and 2, the second aim in Article 3 and the third in Article 4. Conclusion: Based on the results of Articles 1 and 2, the FHT shows normal rate between 8-10 sensory stimuli, with an extinction prevalence associated with the education level and increasing age; The LCT cutoff point to define is USN above 0 and SCT above 2, and both were associated with age. The LBT cutoff point to indicate NEU was 6.6 mm, associated with poorer education level. Article 3 reveals the relationship between a lower hemoglobin level in acute phase of stroke with worse performance on USN tests; Article 4 reports that the effectiveness and safety of pharmacological treatments for USN after stroke remain uncertain, requiring additional randomized clinical trials to evaluate the effect of treatment.
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Martínek, Marek. "Tvorba SW pro generování signálu simulující závady rotačních systémů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442837.
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This diploma thesis deals with the design and creation of an algorithm for generating simulated signal data from a vibration diagnostics device. The first part is focused on theoretical acquaintance with vibration diagnostics and characteristics of individual defects of rotary machines. The next part deals with the possibilities of mathematical and kinematic simulations using a computer software. The main part of this work is dedicated to design and creation of software for generating simulated signal data. In the last part, the principle of simulation of specific defects of rotary machines is clearly demonstrated.
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Walvick, Ronn P. "Magnetic Resonance Imaging of Neural and Pulmonary Vascular Function." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-dissertations/372.
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"Magnetic resonance imaging (MRI) has emerged as the imaging modality of choice in a wide variety experimental and clinical applications. In this dissertation, I will describe novel MRI techniques for the characterization of neural and pulmonary vascular function in preclinical models of disease. In the first part of this dissertation, experimental results will be presented comparing the identification of ischemic lesions in experimental stroke using dynamic susceptibility contrast (DSC) and a well validated arterial spin labeling (ASL). We show that DSC measurements of an index of cerebral blood flow are sensitive to ischemia, treatment, and stroke subregions. Further, we derived a threshold of cerebral blood flow for ischemia as measured by DSC. Finally, we show that ischemic lesion volumes as defined by DSC are comparable to those defined by ASL. In the second part of this dissertation, a methodology of visualizing clots in experimental animal models of stroke is presented. Clots were rendered visible by MRI through the addition of a gadolinium based contrast agent during formation. Modified clots were used to induce an experimental embolic middle cerebral artery occlusion. Clots in the cerebral vasculature were visualized in vivo using MRI. Further, the efficacy of recombinant tissue plasminogen activator (r-tPA) and the combination of r-tPA and recombinant annexin-2 (rA2) was characterized by clot visualization during lysis. In the third part of this dissertation, we present results of the application of hyperpolarized helium (HP-He) in the characterization of new model of experimental pulmonary ischemia. The longitudinal relaxation time of HP-He is sensitive to the presence of paramagnetic oxygen. During ischemia, oxygen exchange from the airspaces of the lungs to the capillaries is hindered resulting in increased alveolar oxygen content which resulted in the shortening of the HP-He longitudinal relaxation time. Results of measurements of the HP-He relaxation time in both normal and ischemic animals are presented. In the final part of this dissertation, I will present results of a new method to measure pulmonary blood volume (PBV) using proton based MRI. A T1 weighted, inversion recovery spin echo sequence with cardiac and respiratory gating was developed to measure the changes in signal intensity of lung parenchyma before and after the injection of a long acting intravascular contrast agent. PBV is related to the signal change in the lung parenchyma and blood before and after contrast agent. We validate our method using a model of hypoxic pulmonary vasoconstriction in rats."
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Termenon, Conde Maite. "Analyse par graphes de la connectivité fonctionnelle de repos par IRM : vers de nouveaux biomarqueurs de la récupération fonctionnelle dans l'AVC." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAS023/document.
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