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1
Hunter, Patricia Jean. "A Dnaj-related co-chaperone, Mrj, is required for placental devlopment in mice." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0001/MQ40792.pdf.
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de, Bock Charles Edo St George Clinical School UNSW. "Novel protein interactors of urokinase-type plasminogen activator receptor." Awarded by:University of New South Wales. St George Clinical School, 2005. http://handle.unsw.edu.au/1959.4/23009.
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The plasminogen activator (PA) system plays an important role in cell adhesion, migration and invasion, and may require the coordinated expression of various proteins. The human urokinase-type plasminogen activator (uPA) receptor (uPAR) is a central protein component of the PA system. By binding its ligand uPA, uPAR can direct proteolysis of the extracellular matrix. Also, it is now apparent that uPAR can initiate proteolytic independent signal transduction to influence angiogenesis, inflammation, wound repair and tumour progression. To determine whether any novel proteins interacted with uPAR, a yeast two-hybrid screening analysis was undertaken using alternate uPAR domain constructs as baits. These included full-length three domain uPAR (uPAR-DIDIIDIII), two domain uPAR (uPAR-DIIDIII), and each individual uPAR domain (uPAR-DI, uPAR-DII and uPAR-DIII). A number of proteins were identified as putative candidate interactors for the alternate constructs, with two of special interest for uPAR-DIDIIDIII. These were the heat shock protein Mrj, and the extracellular matrix protein fibulin-2. The protein Mrj was shown to bind uPAR both in vitro and in vivo using GST-pull down and co-immunoprecipitation assays respectively. The GST-pull down assay identified the interaction between Mrj and uPAR dependent on the C-terminal domain of Mrj and DI of uPAR. Using in vivo co-immunoprecipitation analysis, Mrj also bound to uPAR. Preliminary data suggest the association between uPAR and Mrj may play a role in the regulation of apoptosis. In regard to the uPAR interactor of fibulin-2, a calcium dependent binding interaction with uPAR was identified using the GST-pull down assay. However due to the large molecular weight and stringent conditions needed to solubilise fibulin-2, it was not possible to co-immunoprecipitate both uPAR and fibulin-2. Together, the identification of both Mrj and fibulin-2 amongst other candidate interactors of uPAR presented here provides further insight into the intricate relationship between uPAR and other proteins which may influence a range of biological functions.
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Lin, Zhen St George Clinical School UNSW. "Molecular mechanism of cancer related to urokinase receptor: DNAzyme-mediated inhibition and Novel protein interactors of urokinase receptor." Awarded by:University of New South Wales. St George Clinical School, 2007. http://handle.unsw.edu.au/1959.4/31893.
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The urokinase receptor (uPAR) plays a central role in metastatic process. It???s evident uPAR is overexpressed across a variety of tumour cells and leads to the increased aggressiveness and poor prognosis of cancer. Inhibition of uPAR expression can block metastatic potential in many tumours. In addition, besides uPA, there are several other proteins which have been confirmed to interact with uPAR, such as vitronectin and integrins. These interactions also contribute to signal transduction and the functions of uPAR complex. Therefore, downregulation of uPAR expression by targeting uPAR mRNA or protein, or by regulating the uPAR partners would be potential therapeutic strategies for prevention of cancer metastasis. There are two main aspects contained in this thesis. Firstly, three specific DNAzymes targeting uPAR mRNA were designed to downregulate uPAR expression in vitro and their effects to decrease cancer cell invasion studied in a human osteosarcoma cell line Saos-2. The results showed that two of them (Dz483 and Dz720) cleaved uPAR transcript in vitro with high efficacy and specificity and the Dz720 inhibited uPAR protein levels by 55% in Saos-2 cells. Besides, the Dz720 significantly suppressed Saos-2 cell invasion using an in vitro matrigel assay. Secondly, two potential uPAR partners from yeast two-hybrid screening, a heat shock protein MRJ and an anti-apoptosis protein HAX-1, were characterised and their functions binding with uPAR investigated. The interactions were confirmed by co-immunoprecipitation, GST-pull down assay and confocal microscopy in cancer cells. In addition, there was a 50% increase in cell adhesion after transfection with MRJ. This increase in adhesion is dependent on the uPAR/full length MRJ interaction as cells transfected with the mutant construct containing only N-terminal region or C-terminal region of MRJ had no increase in cell adhesion. The observed increase in adhesion to vitronectin by MRJ was also blocked by an anti-uPAR domain I antibody suggesting that the induced adhesion is at least in part contributed by uPAR on the cell surface. Together, the identification of both MRJ and HAX-1 as uPAR interactors provides further insight into the intricate relationship between uPAR and other proteins which may develop potential approaches for cancer therapy.
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Slovak, Peter Michael. "Characterisation of the mre and mrd loci of Rhodobacter sphaeroides." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414270.
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Inturi, Satya Prakash Reddy, and Chaitanya Macherla. "System Performance of MIMO MRT/MRC System under Perfect CSI." Thesis, Blekinge Tekniska Högskola, Institutionen för datavetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-21137.
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Multiple Input and Multiple Output (MIMO) is one of the techniques used tiimprove the system performance. In this thesis, we improve and evaluate the system performance of MIMO deploying MRT technique at the transmitter and MRCtechnique at the receiver with an assuming that the system can obtain perfect CSI.We derived expressions for outage probability and symbol error rate and simulationgraphs for SISO, SIMO, MISO, and MIMO in terms of outage probability. Our results show that the MIMO system performance is better than other configurations.We also observed that SISO have the least performance where SIMO and MISOhave same performance. The performance also increases as the number of antennasincrease in the system and it is suggested to use MIMO when performance is givehigh priority than cost.
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Chalmers, Kirsten Hardie. "Fluorinated paramagnetic probes for 19-F and 1-H MRS/MRI." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/879/.
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Novel CF3-labelled lanthanide(III) complexes have been synthesised for use as probes for 19-F and 1-H magnetic resonance spectroscopy and imaging. The syntheses and evaluation of two classes of fluorinated paramagnetic complexes are defined. Notably, the 19-F magnetic resonance relaxation processes for the complexes have been assessed, allowing for the analysis of the interplay between applied field, Ln(III) ion and rotational correlation time on relaxation properties. Strategies employed to enhance signal intensity are discussed, examining a number of different of fluorinated mono- and di-amide cyclen ligands. Systems incorporating phosphinate pendant arms are of particular interest, resulting in complexes with favourable isomer distributions, faster longitudinal relaxation rates and narrower linewidths. Finally, the synthesis of high molecular weight conjugates with paramagnetic fluorinated complexes is described. Three different classes of medium to high molecular adducts were considered, with the merits and limitations of each assessed. The desirable formation of one species in solution, ease of solubility and attractive 19F and 1H relaxometric properties render the chitosan conjugates promising candidates for future use as imaging probes.
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Ramamurthy, Senthil. "Localized double-quantum filtered correlated spectroscopy on 3T MRI/MRS scanner." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=4012.
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Thesis (M.S.)--West Virginia University, 2005.<br>Title from document title page. Document formatted into pages; contains ix, 69 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 65-69).
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Chao, Hui Ph D. Massachusetts Institute of Technology. "Multi-echo methods for fast MRI and MRS of ³¹P containing compounds." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43335.
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Chen, Hua Hsuan. "The application of MRI and MRS in psychiatry and performance evaluation of magnetic field homogeneity in MRI : a dissertation /." San Antonio : UTHSC, 2006. http://proquest.umi.com/pqdweb?did=1155567931&sid=1&Fmt=2&clientId=70986&RQT=309&VName=PQD.
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Hejtmánek, Ondřej. "Projekt datového centra - strukturovaná kabeláž." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219768.
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This master’s thesis is concerned with analysis of cabling and cabling systems in data center and with their projection as follows. The part of the work is aimed at the measurement parameters of metal cables which are used in data center with noise. The first part is focused on analyzing the structure of the data center and cabling used in it. The structure of the data center is based on the TIA-942 and consists of an entrance room, main distribution area MDA, horizontal distribution area HDA , zone distribution area ZDA and the equipment distribution area EDA. Divided into backbone cabling and horizontal cabling and use standard and pre-terminated cabling. The measurement results of structured metal cabling with noise are discussed in the next part. There were used these types of cables UTP, FTP and S/FTP. The measurement was performed in the electricity substation and in the laboratory of electromagnetic compatibility. The third part of this work deals with the actual design of structured cabling for the data center. In the first design we use the standard installation, the second preterminated cabling. For both types of installation cost statement is processed (CAPEX). Thesis is also completed with DC design drawings and rack drawings.
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Buckley, Gemma. "Characterisation of the regenerating MRL/MpJ ear wound and the effect of denervation." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.695271.
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Smart, Sean Christopher. "NMR examinations of control and ischemic rodent brain tissue." Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309450.
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Haga, Kristin Kerr. "The combined application of 'H MRI and '19F MRS to the study of cerebroprotection." Thesis, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312006.
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Steger, Ronny. "Einfluss einer MRT-Untersuchung auf die Funktionsstabilität nicht MRT-fähiger Herzschrittmacher und ICD." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-144013.
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Die bildgebende Diagnostik im Magnetresonanztomographen ist für Träger implantierter, nicht MR-fähiger Herzschrittmacher und Cardioverter/Defibrillatoren potentiell risikoreich. Durch das starke externe Magnetfeld und die elektromagnetischen Signale des MRT-Gerätes können die antibradykarden und –tachykarden Therapiesysteme in ihrer korrekten Funktion erheblich gestört und durch die Antennenwirkung der Sonden myokardiale Schädigungen hervorgerufen werden.
In der vorliegenden Arbeit sind bei Trägern derartiger Implantate deren wichtigste Funktionsparameter vor und nach einer jeweiligen Untersuchung im MRT telemetrisch ermittelt worden. Anhand der statistischen Auswertung der prä- und postprozedualen Messwerte für Wahrnehmung (Sensing), Reizschwelle und Elektrodenimpedanz wurde der Einfluss einer MRT-Untersuchung auf die regelrechte Funktion der Herzschrittmacher- und ICD-Aggregate untersucht. Ein weiteres Augenmerk galt im Allgemeinen der grundsätzlichen Durchführbarkeit des Verfahrens und eventuellen Komplikationen hinsichtlich unzureichender Patientensicherheit.
Zum einen konnte gezeigt werden, dass nach sorgfältiger Abwägung von Risiko und Nutzen der Untersuchung, sowie entsprechenden Sicherheitsvorkehrungen, die MRT komplikationslos durchführbar ist. Weiterhin konnte keine Beeinträchtigung der regelrechten Funktion der Aggregate nachgewiesen werden.
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Craig-Craven, Alexander. "Development of Transmit and Receive Coils for 1H MRI/MRS on a 7T MR Scanner." Thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10930.
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<p>High quality images with strong contrast, good resolution and geometrical consistency are of crucial importance in magnetic resonance imaging, where the relatively low intrinsic sensitivity of MR methods places high demands on the imaging hardware. One of many key components in the imaging system is the radiofrequency coil, responsible for transmitting excitation signals and/or listening for response from the object. In this project a number of such coils are developed for specific applications (namely proton imaging of rat and fish brains), then evaluated against phantoms and empirically in simulated imaging situations. Evaluation of the produced coils shows promising initial results, with various opportunities for further refinement into a device suitable for regular use.</p>
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Anderson, Christian Edwin. "High-Field Magnetic Resonance Fingerprinting for Molecular MRI." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case152478492457623.
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Elschner, Cindy. "Analyse der knöchernen Einheilung von Biomaterialien mit der Magnetresonanztomographie." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-204714.
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Die Analyse von Implantat-Gewebe-Wechselwirkungen basiert derzeit hauptsächlich auf histologischen Techniken. Der invasive Charakter der histologischen Präparation lässt allerdings keine Untersuchung am lebenden Tier zu. Dadurch ist es nicht möglich, den Prozess der Implantateinheilung wiederholt an einem Tier zu beobachten. Die Folgen sind eine hohe Anzahl aufzuwendender Versuchstiere und eine Vergrößerung der Messunsicherheit infolge der gestiegenen biologischen Variabilität. Nicht-invasive, bildgebende Verfahren spielen daher eine zunehmende Rolle für die Entwicklung neuer Biomaterialien. Während die Computertomographie (CT) häufig zur Untersuchung der knöchernen Implantateinheilung verwendet wird, hat sich die Nutzung der Magnetresonanztomographie (MRT) für diese Fragestellungen bisher nicht etabliert. Bei der Magnetresonanztomographie handelt es sich, analog zur Computertomographie, um ein bildgebendes Verfahren zur nicht-invasiven Erzeugung digitaler Schnittbilder. Im Gegensatz zur CT, die das Hartgewebe abbildet, wird bei der MRT das Weichgewebe detektiert, wobei keine ionisierende Strahlung verwendet wird. Der große Vorteil der MRT gegenüber anderen bildgebenden Methoden besteht darin, dass es möglich ist, das Weichgewebe auf den Schnittbildern anhand verschiedener Kontraste darzustellen. Zusätzlich können MR-spezifische Parameter quantifiziert werden, die einen direkten Rückschluss auf die Struktur zulassen. Mit diesen Kennzahlen ist es möglich, Veränderungen im Weichgewebe analysieren. Das Ziel der Arbeit war es deshalb, die Eignung und mögliche Anwendungen der Magnetresonanzto-mographie (MRT) zur Analyse der Implantat-Gewebe-Wechselwirkungen zu erörtern. Für die Untersu-chungen wurde ein NMR-Spektrometer inklusive Imaging-Zubehör verwendet. Die Dissertationsarbeit beinhaltete sowohl die Untersuchung verschiedener Materialsysteme hinsichtlich ihrer Eignung für die MRT und deren Biokompatibilität, als auch die Analyse der knöchernen Einheilung ausgewählter Biomaterialien. Diese umfasste Aussagen zur Darstellbarkeit und Abgrenzbarkeit von Strukturen und beinhaltete auch quantitativ gewonnene Messparameter. Die Ergebnisse wurden stets im Vergleich mit der Histologie diskutiert. In der Arbeit konnte dargestellt werden, dass die Überprüfung der Eignung des zu untersuchenden Materials für die MRT vor der Analytik erfolgen muss. Es wurde demonstriert, dass Metalle erheblich mit dem MR-System wechselwirken können, was in der Konsequenz zu drastischen Störungen der Bildqualität führt. Diese Effekte waren stark von den ausgewählten Messparametern abhängig. Als ein MRT-geeignetes Verbundmaterial wurde Titan-beschichtetes Polyetheretherketon (PEEK/Ti) vorgeschlagen. Die Beschichtung mit Titan führte zu einer signifikant verbesserten Biokompatibilität des Kunststoffes. Die erfolgreiche Analyse der knöchernen Einheilung mit der Magnetresonanztomographie wurde im Rahmen von zwei tierexperimentellen Studien an verschiedenen Biomaterialien gezeigt (die Analyse erfolg-te ex vivo). Die Untersuchung der knöchernen Integration eines Zahnimplantates aus PEEK/Ti hatte das Ziel, die Darstellbarkeit des Implantates und knöcherner Strukturen mit der Magnetresonanztomographie zu evaluieren. Außerdem wurde ebenfalls gezeigt, dass es anhand der MRT-Schnittbilder möglich ist, quantitative Messgrößen zur Beschreibung des Einheilprozesses zu gewinnen. Aufgrund der geringen Versuchstierzahl wurde jedoch eine breite Streuung der Messdaten festgestellt. Allerdings besitzt die Studie durch die Untersuchung eines Zahnimplantates aus Polyetheretherketon/Titan mit der MRT nicht nur Neuheitswert in der Biomaterialforschung, sondern schlägt gleichzeitig eine Brücke zur klinischen, dentalen Implantologie. Die Bewertung der Darstellbarkeit knöcherner Strukturen und der verwendeten (teils tissue-engineerten) Knochenersatzmaterialien mit MRT und Histologie und des klinischen Erfolges derselben bildeten einen Schwerpunkt der zweiten tierexperimentellen Studie (die Analyse erfolgte ex vivo). Es war möglich, mit beiden bildgebenden Verfahren zu zeigen, dass sich die verwendeten Knochenersatzmaterialien nicht für die vorgesehene Anwendung eigneten. Die Beurteilung der Übereinstimmung der quantitativ gewonnenen Parameter beider Analysenmethoden bildete den Abschluss der Arbeit. Es wurde festgestellt, dass zwischen den Messdaten stets ein syste-matischer Unterschied bestand. Nachweislich war dieser aber weniger das Resultat der ungleichen lateralen Auflösungen oder der unterschiedlichen Darstellbarkeit von Gewebestrukturen der beiden Verfahren, sondern konnte auf den Einfluss der Analyse verschiedener Schichtebenen und individueller Unterschiede bei der digitalen Quantifizierung der auswertenden Personen zurückgeführt werden<br>Currently, histological techniques are used to analyse implant-tissue-interactions. However, these methods are destructive and do not allow for the investigation of living animals. Therefore, it is not possible to study the integration of biomaterials repeatedly with one animal, resulting in a large number of animals and an increase of biological variability. Non-invasive imaging techniques have gained interest in the field of biomaterials. Whereas Computed Tomography (CT) was often used to evaluate the osseous integration, the assessment using Magnetic Resonance Imaging (MRI) has not been established, yet. MRI is a non-invasive medical imaging method that detects soft tissue. In contrast to CT the method does not require individuals to be exposed to radiation. The most important benefit of MRI is the possibility to acquire different soft tissue contrasts in situ because the various tissues have different signal intensities on MR images that can be altered by using different experimental parameters. Furthermore, it is possible to gain MR-specific properties that allow conclusions to the tissue structure. Thus, the objective of the doctoral thesis has been to investigate the suitability of MRI for the use in biometerial research and to show potential areas of application. The examinations were performed using a laboratory NMR-spectrometer inclusive imaging accessory. The thesis included an evaluation of the MR compatibility of different materials and their biocompati-bility and an analysis of the ingrowth of chosen biomaterials into bone. For that, the detection and identification of tissue structures and biomaterials was investigated with both, MRI and histology. Additionally, quantitative parameters were acquired and their comparability was assessed. It was clearly demonstrated, that metals interacted with the MR system and provoked large image distortions. These effects were strongly dependent on experimental parameters chosen. Polyetheretherketone with titanium coating (PEEK/Ti) was investigated and has been found to be MR safe. Above all, it was demonstrated that the biocompatibility of the polymer was significantly enhanced by coating with titanium. Within two animal studies the successful analysis of the osseous healing of different biomaterials with MRI was presented. To demonstrate the visibility of bony structures and biomaterials a dental implant made of PEEK/Ti was analysed. The ability to measure quantitative data in analogy to histomorphometry was shown, ditto. A large variation of the values was detected due to the limited number of animals used for the pilot study. Evaluating the displayability of bone and (to some extent tissue engineered) bone substitutes and assessing the clinical success of these materials was one main focus of the second animal study. Both, MRI and histological analysis could undeniably illustrate that all of the bone substitutes were not suitable for the chosen application. The thesis was completed with the determination of the agreement of quantitative values from both analysing methods. It was concluded that all values gained from the animal study were significantly different. It was proven that the chosen slice position and the image interpretation with two evaluators had a larger share to disagreement than the different lateral resolution of MRI and histological images or the diverging displayability of bone and bone substitutes. By investigating a MR suitable dental PEEK implant the doctoral thesis fulfils the criteria of novelty in biomaterial research. Moreover, it forges links between preclinical research and dental implantology
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Brown, David Gerald. "Instrumentation for parallel magnetic resonance imaging." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4784.
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Parallel magnetic resonance (MR) imaging may be used to increase either the
throughput or the speed of the MR imaging experiment. As such, parallel imaging may
be accomplished either through a "parallelization" of the MR experiment, or by the use
of arrays of sensors. In parallelization, multiple MR scanners (or multiple sensors) are
used to collect images from different samples simultaneously. This allows for an
increase in the throughput, not the inherent speed, of the MR experiment. Parallel
imaging with arrays of sensor coils, on the other hand, makes use of the spatial
localization properties of the sensors in an imaging array to allow a reduction in the
number of phase encodes required in acquiring an image. This reduced phase-encoding
requirement permits an increase in the overall imaging speed by a factor up to the
number of sensors in the imaging array. The focus of this dissertation has been the
development of cost-effective instrumentation that would enable advances in the state of
the art of parallel MR imaging.
First, a low-cost desktop MR scanner was developed (< $13,000) for imaging small
samples (2.54 cm fields-of view) at low magnetic field strengths (< 0.25 T). The
performance of the prototype was verified through bench-top measurements and
phantom imaging. The prototype transceiver has demonstrated an SNR (signal-to-noise ratio) comparable to that of a commercial MR system. This scanner could make
parallelization of the MR experiment a practical reality, at least in the areas of small
animal research and education.
A 64-channel receiver for parallel MR imaging with arrays of sensors was also
developed. The receiver prototype was characterized through both bench-top tests and
phantom imaging. The parallel receiver is capable of simultaneous reception of up to
sixty-four, 1 MHz bandwidth MR signals, at imaging frequencies from 63 to 200 MHz,
with an SNR performance (on each channel) comparable to that of a single-channel
commercial MR receiver. The prototype should enable investigation into the speed
increases obtainable from imaging with large arrays of sensors and has already been
used to develop a new parallel imaging technique known as single echo acquisition
(SEA) imaging.
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Hu, Ruomin [Verfasser], and Lothar [Akademischer Betreuer] Schad. "Exploring Quadrupolar Interactions of 23Na and 35Cl with Triple-Quantum MRS/MRI / Ruomin Hu ; Betreuer: Lothar Schad." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1206416726/34.
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Williams, Rebecca Elizabeth. "Biochemical and neurotoxicological effects of L-2-chloropropionic acid on the brain : an MRS and MRI study." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243458.
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Hu, Ruomin [Verfasser], and Lothar R. [Akademischer Betreuer] Schad. "Exploring Quadrupolar Interactions of 23Na and 35Cl with Triple-Quantum MRS/MRI / Ruomin Hu ; Betreuer: Lothar Schad." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-281022.
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Ermisch, Jörg. "Die fetale Hirnentwicklung zwischen der 16. -und 30. Schwangerschaftswoche- Eine postmortale Untersuchung von 117 Feten am 3Tesla- MRT." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-115179.
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Für die Beurteilung der Hirnentwicklung erfolgte eine postmortale MRT- Untersuchung von totgeborenen Kindern im Rahmen einer virtuellen Autopsie.
Besondere Berücksichtigung innerhalb dieses Datenmaterials fand die Oberflächenveränderung im Sinne der Entstehung von Gyri und Sulci. Weiterhin wurde geprüft, wie sich die morphologische Entwicklung und damit die Germination und Migration der Nervenzellen in diesem Schwangerschaftszeitraum in der MRT darstellen und beurteilen lässt.
Im Ergebnis der Untersuchung zur Germination und Migration war vor allem zwischen der 18. und 25. SSW die zonale Gliederung des Hirnmantels mit “ventricular zone“, “intermediate zone“, “subplate zone“ und “cortical plate“ durch wechselnde Hypo –bzw. Hyperintensitäten in der MRT gut zu beurteilen.
Der zeitlich geordnete Ablauf in der Entstehung einzelner Sulci konnte in dieser Arbeit unter anderem auch mittels eines atlasartigen Teils abgebildet werden.
Dabei zeigte sich eine häufig etwas frühere Darstellbarkeit einzelner Sulci im postmortalen MRT im Vergleich zu den Studien an pränatalen MRT´s bei Schwangeren. Eine Streubreite des Auftretens der einzelnen Sulci von 2-3 Wochen bei gesunden Feten ist dabei zu berücksichtigen.
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Huber, Laurentius. "Mapping Human Brain Activity by Functional Magnetic Resonance Imaging of Blood Volume." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-165252.
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This dissertation describes the development, implementation, validation, optimization, and application, of a noninvasive and quantitative method for measuring cerebral blood volume changes with functional magnetic resonance imaging (fMRI) for mapping of neural activity changes.
Since its inception over twenty years ago, the field of fMRI has grown in usage, sophistication, range of applications, and impact. Nevertheless it has yet to exploit its full potential regarding, spatiotemporal resolution, signal specificity, and quantifiability of hemodynamic changes. By utilization of a new MR pulse sequence, new concepts of radio frequency pulses, and high magnetic fields (7 T), a novel fMRI method named SS-SI VASO is presented here that overcomes sensitivity limitations of other noninvasive quantitative imaging methods. In order to validate that its signal represents changes in cerebral blood volume without other contaminations, SS-SI VASO is implemented in animal models for a close comparison with established, but invasive methods. A good agreement of blood volume sensitivity has been found with the new method compared to the established ones. After its validation, the SS-SI VASO method and its unprecedented sensitivity was used to localize and quantify hemodynamic changes in applications where conventional oxygenation based fMRI methods are limited. (A) SS-SI VASO was used to investigate biophysical aspects of actively controlled arteries and passive balloon-like veins during activity induced hemodynamic changes. (B) SS-SI VASO was used to provide insights whether the interplay of neural activity and resultant vascular response are the same for tasks that increase neural activity compared to tasks that suppress neural activity. (C) SS-SI VASO was used to calibrate conventional oxygenation based fMRI to quantify local changes in oxygen metabolism. (D) The high sensitivity of SS-SI VASO was further used to obtain sub-millimeter resolutions and estimate activity changes between cortical layers. This enables to address questions not only where the brain is activated but also how and whereby this activity is evoked. The implementation and application of this new SS-SI VASO fMRI method is a major step forward for the field of imaging neuroscience; it demonstrates that the current limitations of fMRI can be even overcome with respect to quantifiability, spatial specificity and distinguishing between vascular and neuronal phenomena.
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Daniels, Barret R. "Magnetic Resonance Guided Nasojejunal Feeding Tube Placement for Neonates." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439281638.
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Yan, Jiun-Lin. "Characterising peritumoural progression of glioblastoma using multimodal MRI." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267740.
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Glioblastoma is a highly malignant tumor which mostly recurs locally around the resected contrast enhancement. However, it is difficult to identify tumor invasiveness pre-surgically, especially in non-enhancing areas. Thus, the aim of this thesis was to utilize multimodal MR technique to identify and characterize the peritumoral progression zone that eventually leads to tumor progression. Patients with newly diagnosed cerebral glioblastoma were included consecutively from our cohort between 2010 and2014. The presurgical MRI sequences included volumetric T1-weighted with contrast, FLAIR, T2-weighted, diffusion-weighted imaging, diffusion tensor and perfusion MR imaging. Postsurgical and follow-up MRI included structural and ADC images. Image deformation, caused by disease nature and surgical procedure, renders routine coregistration methods inadequate for MRIs comparison between different time points. Therefore, a two-staged non-linear semi-automatic coregistration method was developed from the modification of the linear FLIRT and non-linear FNIRT functions in FMRIB’s Software Library (FSL). Utilising the above mentioned coregistration method, a volumetric study was conducted to analyse the extent of resection based on different MR techniques, including T1 weighted with contrast, FLAIR and DTI measures of isotropy (DTI-p) and anisotropy (DTI-q). The results showed that patients can have a better clinical outcome with a larger resection of the abnormal DTI q areas. Further study of the imaging characteristics of abnormal peritumoural DTI-q areas, using MRS and DCS-MRI, showed a higher Choline/NAA ratio (p = 0.035), especially higher Choline (p = 0.022), in these areas when compared to normal DTI-q areas. This was indicative of tumour activity in the peritumoural abnormal DTI-q areas. The peritumoural progression areas were found to have distinct imaging characteristics. In these progression areas, compared to non-progression areas within a 10 mm border around the contrast enhancing lesion, there was higher signal intensity in FLAIR (p = 0.02), and T1C (p < 0.001), and there were lower intensity in ADC (p = 0.029) and DTI-p (p < 0.001). Further applying radiomics features showed that 35 first order features and 77 second order features were significantly different between progression and non-progression areas. By using supervised convolutional neural network, there was an overall accuracy of 92.4% in the training set (n = 37) and 78.5% in the validation set (n=14). In summary, multimodal MR imaging, particularly diffusion tensor imaging, can demonstrate distinct characteristics in areas of potential progression on preoperative MRI, which can be considered potential targets for treatment. Further application of radiomics and machine learning can be potentially useful when identifying the tumor invasive margin before the surgery.
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Pierre, Eric Y. "Reliable Use of Acquired and Simulated Signal Databases to Reduce MRI Acquisition Time." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1404220001.
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Leclair, Nadine Stéfanie. "Diffusionsgewichtete Ganzkörper-MR-Bildgebung bei Kindern mit Chronischer Rekurrierender Multifokaler Osteomyelitis." Doctoral thesis, Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-218109.
Full textAbstract:
Zielsetzung: Die Chronisch-Rekurrierende Multifokale Osteomyelitis/Chronische Nicht-bakterielle
Osteitis (CRMO/CNO) ist eine seltene auto-inflammatorische Erkrankung, deren typische Symptome
starke Knochenschmerzen und lokale Schwellungen sind. Da die Ursachen muskuloskelettaler
Beschwerden bei Kindern und Heranwachsenden vielfältig sein können, ist die
differentialdiagnostische Unterscheidung einer CRMO/CNO von anderen Erkrankungen,
unspezifischen Schmerzen oder einer malignen Grunderkrankung als Quelle der Symptome schwierig.
Neue Techniken wie die diffusionsgewichtete Bildgebung (DWI) in der Magnetresonanztomographie
(MRT) erlauben Rückschlüsse auf die Gewebestruktur und können in bestimmten Fällen eine
Unterscheidung zwischen entzündlichen und malignen Prozessen vereinfachen. Ziel dieser Studie war
es daher, die Sichtbarkeit von CRMO-/CNO-Läsionen mittels der DWI-Ganzkörperbildgebung zu
evaluieren und den potentiellen klinischen Wert zu untersuchen.
Material und Methoden: Sechzehn Patienten mit bekannter CRMO/CNO wurden bei 3 Tesla
untersucht. Das Untersuchungsprotokoll beinhaltete u. a. 2D Short Tau Inversion Recovery (STIR)
und diffusionsgewichtete Sequenzen in axialer Schichtführung. Die Sichtbarkeit von Läsionen in der
DWI und der STIR wurde von 2 Auswertern im Konsensus evaluiert. Für alle Läsionen und in der
korrespondierenden Referenzlokalisation wurden der Apparent Diffusion Coefficient (ADC) ermittelt.
Ergebnisse: Insgesamt wurden 33 Läsionen eingeschlossen (durchschnittlich 2 Läsionen pro Patient),
die sowohl in der STIR als auch in der DWI sichtbar waren. Diese waren vornehmlich in den langen
Röhrenknochen lokalisiert. Der mittlere ADC-Wert in Läsionen betrug 1283 mm2/s und war somit
signifikant höher als in der Referenzregion, hier betrug der mittlere ADC 782 mm2/s. Im ADCVerhältnis
(Läsion vs. Referenzregion) zeigten 82 % der Läsionen eine relative
Signalintensitätssteigerung um mehr als 10 %, und 76 % (25 Läsionen) zeigten eine
Intensitätssteigerung von mehr als 15 %. Der mittlere relative Signalintensitätsanstieg betrug 69 %.
Schlussfolgerung: Diese Studie zeigt, dass die diffusionsgewichtete Ganzkörperbildgebung bei 3 Tesla
zuverlässig bei Kindern durchgeführt werden kann. Die ADC-Werte waren in CRMO-/CNO-Läsionen
im Vergleich zur Referenzregion signifikant erhöht. Daher wird die Ganzkörperbildgebung in
Kombination mit klinischen Angaben von uns als vielversprechende Methode angesehen, um benigne
inflammatorische Prozesse anhand der ADC-Werte von bestimmten Malignitäten zu unterscheiden.
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Kim, Kisoo. "Interventional MR Elastography for the monitoring of thermal ablations." Thesis, Strasbourg, 2019. https://publication-theses.unistra.fr/public/theses_doctorat/2019/Kim_Kisoo_2019_ED269.pdf.
Full textAbstract:
L'ablation thermique vise à endommager les cellules tumorales en chauffant ou en congelant le tissu tumoral. La surveillance par IRM est une technique prometteuse pour assurer la destruction des cellules tumorales tout en aidant à préserver les tissus sains environnants. L'équipe ICube a récemment proposé l'utilisation de l'élastographie RM en temps réel (MRE) et de la thermométrie RM (MRT). Cela permet de surveiller la température et les propriétés mécaniques du tissu ciblé simultanément en temps réel. Dans cette thèse de doctorat , nous avons présenté deux développements différents afin de surmonter certaines des limitations actuelles de la MRE et de la MRT interventionnelles, en termes d’extension à la couverture spatiale de la région ciblée et au développement d’une nouvelle méthode de surveillance des ablations thermiques pour tous les types de tissus mous, y compris les tissus adipeux. Ces contributions visent à améliorer la sécurité et l'efficacité de l'ablation thermique guidée par MR<br>Thermal ablation aims at damaging tumor cells by either heating or freezing tumoral tissue. MRI monitoring is a promising technique for ensuring the destruction of tumor cells while preserving the surrounding healthy tissue. Recently, the ICube team demonstrated the use of simultaneous realtime MR Elastography (MRE) and MR Thermometry (MRT). It allows monitoring temperature and mechanical properties of the targeted tissue simultaneously in realtime. In this Ph.D. thesis, we have presented two different developments in order to overcome some of the current limitations of interventional MRE and MRT, in terms of extending to the spatial coverage of the targeted region and developing a new method to monitor thermal ablations for all types of soft tissues, including fatty tissues. These contributions aim at improving the safety and efficiency of MR guided thermal ablation
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Johannesson, Åsa. "Två radiologiska metoder för diagnostik av pankreascancer, multidetektor datortomografi och magnetisk resonans : En litteraturstudie." Thesis, Örebro universitet, Institutionen för hälsovetenskap och medicin, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-23310.
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Sammanfattning Inledning: Den årliga incidensen för pankreascancer är 9 per 100 000 invånare. En tidig diagnos ger förbättrad 5-årsöverlevnad men botar fortfarande få patienter. De senaste åren har den dåliga prognosen förbättras tack vare utvecklingen inom bilddiagnostiken. Författaren i denna litteraturstudie har valt att jämföra multidetektor datortomografi (MDCT) och magnetisk resonans (MR) med kontrastmedel för diagnostik av pankreastumör vid misstänkt pankreascancer. Syfte: Syftet med denna litteraturstudie är att undersöka vilken radiologisk undersökningsmetod som är att föredra vid diagnostisering av pankreascancer, MDCT eller MR. Frågeställning: Är det MDCT eller MR som är bäst vid diagnostisering av pankreascancer? Metod: En litteraturstudie baserad på 12 antal artiklar som är funna i databasen PubMed. Resultat: MDCT och MR har likvärdig diagnostisk säkerhet att upptäcka pankreastumör samt påvisa kärlinväxt och förutse operabilitet. Båda metoderna har en jämförbar hög noggrannhet för karakterisering av förändringens aggressivitet. Slutsats: Såväl MDCT och MR är likvärdiga två mycket bra radiologiska metoder för att diagnostisera pankreascancer. MDCT har fortfarande en större tillgänglighet är MR men dess nackdel är man utsätter patienterna för joniserande strålning. MR är därför en metod att föredra och med stor sannolikhet kommer dess tillgänglighet att öka kraftigt i framtiden.
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Nguyen, Thanh Thao [Verfasser], and Irina [Akademischer Betreuer] Mader. "Functional MRI and DTI fiber tracking in patients with gliomas = Funktionelle MRT und DTI Fiber Tracking bei Patienten mit Gliomen." Freiburg : Universität, 2011. http://d-nb.info/1123461236/34.
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Kleimaier, Dennis [Verfasser], and Lothar [Akademischer Betreuer] Schad. "Exploring Protein Interactions with 23Na Triple-quantum MRS and 1H Chemical Exchange Saturation Transfer MRI / Dennis Kleimaier ; Betreuer: Lothar Schad." Heidelberg : Universitätsbibliothek Heidelberg, 2021. http://d-nb.info/1227155832/34.
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Kleimaier, Dennis [Verfasser], and Lothar R. [Akademischer Betreuer] Schad. "Exploring Protein Interactions with 23Na Triple-quantum MRS and 1H Chemical Exchange Saturation Transfer MRI / Dennis Kleimaier ; Betreuer: Lothar Schad." Heidelberg : Universitätsbibliothek Heidelberg, 2021. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-293608.
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Borges, Renato Callado. "Ferramentas computacionais para a síntese de imagens de difusão por ressonância magnética." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/45/45134/tde-23042014-120357/.
Full textAbstract:
Trabalhos anteriores sobre a síntese de imagens de difusão por ressonância magnética se limitaram a estudos sobre estruturas microscópicas, menores que as dimensões típicas de um voxel (e.g., [BF08] [BF13] [LFS + 10] e [BA94]). Isto decorre em parte devido às metodologias utilizadas, que têm como ponto em comum serem simulações de tipo Monte Carlo, nas quais os elementos mínimos da simulação são as partículas de água. Portanto o custo computacional destas simulações é proporcional ao número de partículas a simular, e isto limita os volumes que podem ser simulados a tamanhos microscópicos. Propomos uma metodologia alternativa, que utiliza a imagem T 2 de uma amostra para sintetizar imagens de difusão por ressonância magnética. Os elementos mínimos desta nova metodologia são os pontos da imagem T 2 , e portanto seu custo computacional é proporcional à resolução da imagem T 2 utilizada, o que permite a síntese a partir de amostras de qualquer tamanho físico. Estas sínteses são realizadas por meio da integração numérica da equação do artigo seminal de Stejskal e Tanner [ST65] que relaciona a atenuação do sinal de ressonância magnética devida à difusão com os parâmetros da sequência de pulsos PGSE. Usamos os parâmetros típicos dessa sequência (b, gamma, tau\', g 0, g, delta e Delta), que podem ser configurados explicitamente em máquinas de ressonância magnética, para calcular valores do coeficiente de difusão aparente D em direções arbitrárias. Desenvolvemos software, disponibilizado [Bor] por licença GPL [Fou07], para realizar estas simulações, e para especificar uma máscara de direções, útil para modelar a difusão de uma amostra. Estas ferramentas permitem o estudo sistemático das variações dos parâmetros na síntese de imagens de difusão por ressonância magnética. Apresentamos um estudo de um fantoma de capilares imersos em água, exemplificando como utilizar as ferramentas para investigar a influência destes parâmetros na difusão da água da amostra.<br>Previous work on the synthesis of diffusion-weighted magnetic resonance imaging are limited to microscopic structures, smaller than the typical dimensions of a single voxel (e.g., [BF08] [BF13] [LFS + 10] and [BA94]). This is consequence, in part, of the methodologies used, that have in common the adoption of Monte Carlo simulation strategies, in which the minimal elements of simulation are the water particles. Therefore the computational cost of these simulations is proportional to the number of particles to simulate, and this limits the volume to be simulated to microscopic sizes. We propose a novel methodology, that uses the T 2 image from a sample to synthesize diffusion-weighted magnetic resonance images. The mininal elements of this novel methodology are the points of the T 2 image, and therefore its computational cost is proportional to the resolution of the T 2 image to be used, which allows the synthesis from samples of any physical size. These syntheses are made through numerical integration of the equation from the seminal article by Stejskal and Tanner [ST65] that relates the attenuation of the magnetic resonance signal due to diffusion to the parameters of the PGSE pulse sequence. We use the typical parameters of this sequence (b, gamma, tau\', g 0, g, delta and Delta), that can be explicitly configured in magnetic resonance machines, to calculate apparent diffusion coefficients D in arbitrary directions. We developed software, available [Bor] through GPL license [Fou07], to run these simulations, and to specify a mask of directions useful to model diffusion. These tools allow the systematic study of parameter variation in the synthesis of diffusion-weighted magnetic resonance images. We present a case study of a phantom made of capillary tubes immersed in water, to exemplify the use of these tools and how to investigate the influence of parameter variation on diffusion in the sample.
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Riedel, Tim. "Experimentelle und klinische Evaluation eines Navigationssystems für Interventionen an einem herkömmlichen MRT." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-104636.
Full textAbstract:
Mit Hilfe eines kommerziellen, am Universitätsklinikum Leipzig vorhandenen
Navigationssystems (Localite) ist es möglich, Interventionen in einer herkömmlichen MRTUmgebung
unter Echtzeitnavigation durchzuführen. In der vorliegenden Arbeit werden die
Genauigkeit, Benutzerfreundlichkeit sowie der Zeitaufwand für perkutane Punktionen mit
diesem System untersucht.
Zur Navigation wird das jeweilige Instrument optisch verfolgt. Die automatische
Patientenregistrierung außerhalb des MR-Tunnels erfolgt über eine einmalige 3DLokalisation
spezieller MR-Marker. 24 Operateure mit unterschiedlicher radiologischer
Erfahrung führten insgesamt 240 unterschiedlich schwere Punktionen an einem selbst
entwickelten Phantom durch. Nach diesen Versuchen füllten die Operateure einen Fragebogen
zur Handhabbarkeit des Systems aus. Zudem wurden 24 klinische perkutane Interventionen in
nicht atemverschieblichen Körperregionen ausgewertet. Für alle Biopsien wurden Zeiten für
charakteristische Arbeitsschritte dokumentiert.
Die Treffergenauigkeit war im Phantomexperiment für alle Gruppen relativ hoch (Fachärzte:
93%, Assistenzärzte: 88%, Studenten 81%; Cochran p=0,104). Die dazugehörigen
durchschnittlichen Zeiten für einen Biopsiezyklus lagen, gemessen in Minuten, bei 4:13 (FÄ),
4:42 (AÄ) und 5:06 (MS) (P<0,001). Die subjektiven Bewertungen des Navigationssystems
an Hand der Aussagen (Items) des Fragebogens zeigten keine Abhängigkeit vom
Erfahrungsgrad des Operateurs. Die diagnostische Genauigkeit der klinischen Interventionen
lag bei 92%. Die mittlere Interventionszeit betrug dabei 18 min.
Das Navigationssystem wurde erfolgreich für Interventionen in verschiedenen
Körperregionen eingesetzt. Die Genauigkeit und die benötigten Eingriffszeiten sind mit
anderen in der Literatur beschriebenen MRT-geführten Interventionen vergleichbar. Auch
unerfahrene Operateure konnten das Navigationssystem relativ schnell und sicher anwenden.
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Norèn, Ulf, and Sebastian Palmred. "Magnetresonanstomografi med diffusionsprotokoll vid stroke : En retrospektiv deskriptiv studie." Thesis, Uppsala universitet, Radiologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-296220.
Full textAbstract:
ABSTRACT Aim: The aim of this retrospective study was to identify which indications prompted an MRI examination using the protocol ”Brain screening/Stroke” and whether the screening revealed recent infarcts and their localisation. Method: The data, which was subtracted from RIS (Röntgeninformationssystem), covered all consultation responses from stroke-rounds performed during 2015 at Akademiska Hospital in Uppsala (UAS). A total of 235 patients underwent an MRI-examination using the protocol ”Brain screening/Stroke”. Of this total population, 9 patients with a suspected or confirmed tumour were excluded. The information was collected at UAS during the period 11-22 April, 2016. Results: No indications were reported from the material collected. Hence, the method was insufficient to give an answer to the question at hand. In the final selection of 226 patients, no stroke could be detected in 42 % of the cases, 23 % had recent infarcts, 21 % had both recent and old infarcts and 14 % had only old infarcts. By gender the results were as follows: Of the total population, 85 patients were female. In 48% of these cases no stroke was detected, 21 % had recent infarcts, 20 % had old infarcts and 11 % had both recent and old infarcts. The remaining 142 patients were male. In 38% of these no stroke was detected, in 27% of the cases both an old an a recent stroke were detected , in 24% of the cases a recent stroke was detected and 11% had only old infarcts. Looking again at the total population, the consultation responses mentioned only recent infarcts and where these were located. The majority of the recent infarcts detected, 23 % were located in the Lobes of the brain, followed by 16% in the Cortex of the brain, 16% in the Brainstem, 13% in the Cerebellum, 10 % were locaded in ”Other parts of the brain”, 8 % were in the Talamus, 7 % were in White matter and the final 6 % in the Basala ganglia. The total number of recent infarcts detected was 189. Conclusion: The main question for this study was to see if it was possible to discover acute infarcts, using diffusion weighted MRI, and the localisation of those discovered. The method chosen worked well, but to get a better overview, more studies should be done, examining infarcts in greater detail. This knowledge may, in turn, be used as a basis for stroke diagnosis. It might also be of interest to complete this study, with a more in-depth analysis of the connection between different kinds of infarcts and the patient’s gender and age.
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Dhital, Bibek. "Characterizing Brain White Matter with Diffusion-Weighted Magnetic Resonance." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-180140.
Full textAbstract:
It has been known for almost two decades that the water proton NMR signal of diffusing water molecules in brain white matter undergoes a non-monoexponential decay with increasing diffusion gradient factor b. With the help of numerical simulations and analytical expressions, much effort has been directed to describing the signal decay and to extracting relevant biophysical features of the system under investigation. However, the physical basis of such nonmonoexponential behavior is still not properly understood.
The primary difficulty in characterizing this phenomenon is the variation in behavior in the different directions of diffusion measurement. A combined framework that accounts for the diffusion process in all directions requires several parameters. Addition of many such parameters renders a model to be unwieldy and over-complicated, but over-simplifications can be shown to miss crucially relevant information in the data.
In this thesis, I have attempted to handle this problem with simple measurements that span a wide range of parameter space. Compared to often-performed measurements that probe diffusion over a time-scale of 50-100 ms with relatively low diffusion weighting, the measurements here have been done for very short diffusion times of 2 ms and also very long diffusion times up to 2 s. The temperature dependence of the diffusion coefficients has also been extensively probed. To avoid problems related to gross tissue heterogeneity, diffusion-weighted MR imaging in vivo was performed with ultra-high resolution. These simple measurements allowed sequential assessment of many possible arguments that could have led to such non-monoexponential decay curves. Finally, it was concluded that the water in the glial processes was the major contributor to the non-exponential decay, giving rise to a \'slow\' component both along the axonal fibers and transverse to them.
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Peterson, Erika. "Synthetic MRI for visualization of quantitative MRI." Thesis, Linköpings universitet, Avdelningen för radiologiska vetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-102651.
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Magnetic resonance imaging (MRI) is an imaging technique that is used in hospitals worldwide. The images are acquired through the use of an MRI scanner and the clinical information is provided through the image contrast, which is based on the magnetic properties in biological tissue. By altering the scanner settings, images with different contrast properties can be obtained. Conventional MRI is a qualitative imaging technique and no absolute measurements are performed. At Center for Medical Imaging and Visualization (CMIV) researchers are developing a new MRI technique named synthetic MRI (SyMRI). SyMRI is based on quantitative measurements of data and absolute values of the magnetic properties of the biological tissue can be obtained. The purpose of this master thesis has been to take the development of SyMRI a step further by developing and implementing a visualization studio for SyMRI imaging of the human brain. The software, SyMRI Brain Studio, is intended to be used in clinical routine. Input from radiologists was used to evaluate the imaging technique and the software. Additionally, the requirements of the radiologists were converted into technical specifications for the imaging technique and SyMRI Brain Studio. Additionally, validation of the potential in terms of replacing conventional MRI with SyMRI Brain Studio was performed. The work resulted in visualization software that provides a solid formation for the future development of SyMRI Brain Studio into a clinical tool that can be used for validation and research purposes. A list of suggestions for the future developments is also presented. Future clinical evaluation, technical improvements and research are required in order to estimate the potential of SyMRI and to introduce the technique as a generally used clinical tool.
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Kotowski, Susan E. "Understanding a Low Back Pain Pathway: Utilizing MRI and MRS to Link Pain Due to Muscle Inflammation to Changes in Brain Metabolites." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1243367529.
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Mirus, Matthew M., Sergey V. Tokalov, Gerald Wolf, Jerilyn Heinold, V. Prochnow, and Nasreddin Abolmaali. "Noninvasive assessment and quantification of tumour vascularisation using MRI and CT in a tumour model with modifiable angiogenesis – An animal experimental prospective cohort study." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232305.
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Background
To investigate vascular-related pathophysiological characteristics of two human lung cancers with modifiable vascularisation using MRI and CT.
Methods
Tumour xenografts with modifiable vascularisation were established in 71 rats (approval by the Animal Care Committee was obtained) by subcutaneous transplantation of two human non-small-cell lung cancer (NSCLC) cells (A549, H1299) either alone or co-transplanted with vascular growth promoters. The vascularity of the tumours was assessed noninvasively by MRI diffusion-weighted-imaging (DWI), T2-weighted, and time-of-flight (TOF) sequences) as well as contrast-enhanced CT (CE-CT), using clinical scanners. As a reference standard, histological examinations (CD-31, fluorescent beads) were done after explantation.
Results
Microvessel density (MVD) was higher in co-transplanted tumours (171 ± 19 number/mm2) than in non-co-transplanted tumours (111 ± 11 number/mm2; p = 0.002). Co-transplanted tumours showed higher growth rates and larger tumour vessels at TOF-MRI as well as larger necrotic areas at CE-CT. In co-transplanted tumours, DWI revealed higher cellularity (lower minimal ADCdiff 166 ± 15 versus 346 ± 27 mm2/s × 10−6; p < 0.001), highly necrotic areas (higher maximal ADCdiff 1695 ± 65 versus 1320 ± 59 mm2/s × 10−6; p < 0.001), and better-perfused tumour stroma (higher ADCperf 723 ± 36 versus 636 ± 51 mm2/s × 10−6; p = 0.005). Significant correlations were found using qualitative and quantitative parameters: maximal ADCperf and MVD (r = 0.326); maximal ADCdiff and relative necrotic volume on CE-CT (r = 0.551); minimal ADCdiff and MVD (r = −0.395).
Conclusions
Pathophysiological differences related to vascular supply in two human lung cancer cell lines with modifiable vascularity are quantifiable with clinical imaging techniques. Imaging parameters of vascularisation correlated with the results of histology. DWI was able to characterise both the extent of necrosis and the level of perfusion.
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Jiang, Yun. "DEVELOPMENT OF NOVEL PULSE SEQUENCES FOR MAGNETIC RESONANCE FINGERPRINTING." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1480691677961147.
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Fromme, Vivian. "Computertomographische und magnetresonanztomographische Anatomie der Speicheldrüsen der Katze." Doctoral thesis, Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-224710.
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Zielstellung: Die Verwendung von Computertomographie und Magnetresonanzto-mographie zur Diagnostik von pathologischen Weichteilveränderungen, wie Läsionen der Speicheldrüsen, wird empfohlen. Diese begründet sich in Ihrer hohen Bildauflö-sung und dem guten Bildkontrast. Nach unserem Wissen gibt es aktuell keine publi-zierte Literatur, welche sich mit der CT- oder MRT-Anatomie der Speicheldrüsen der Katze beschäftigt. Ziel der vorliegenden Arbeit war es daher, Schnittbildmerkmale der Speicheldrüsen zu definieren und Landmarken für eine sichere Identifikation zu be-schreiben. Material und Methoden: Es wurden zwei Gruppen von Katzen untersucht. Die pros-pektiv untersuchten Tiere bestanden aus 16 Katzen, welche aus Gründen euthana-siert wurden, die nicht in Zusammenhang mit der Studie standen. Diese erfuhren ein CT (1 mm Schichtdicke) und 0,5 Tesla MRT (T2W, T2W SPIR, PDW, T1W) des Kop-fes. Im retrospektiven Anteil der Studie wurden CT-Untersuchungen (0,8-1 mm Schichtdicke) von 25 Katzen und MRT-Untersuchungen (T2W, T1W vor und nach Kontrastmittelgabe) von 21 Katzen verwendet. Diese Untersuchungen wurden zwi-schen 2005 und 2013 in unserer Klinik angefertigt. Dabei konnten keine Pathologien in Zusammenhang mit den Speicheldrüsen festgestellt werden. Alle Speicheldrüsen wurden bezüglich Identifizierbarkeit, Abgrenzbarkeit, Größe und Signalverhalten un-tersucht. Wenn vorhanden, wurden anatomische Landmarken die Speicheldrüsen umgebend notiert. Zusammenfassung 80 Ergebnisse: 94,3% der Glandulae parotidae, 90,7% der Glandulae mandibulares und 96,8% der Glandulae zygomaticae konnten mit dem CT identifiziert werden. Beim MRT waren es 94,1% der Glandulae parotidae, 99,2 % der Glandulae mandibulares, 88,9% der Glandulae zygomaticae und 51,4 % der Glandulae buccalis ventralis. In beiden Gruppen konnten keine der restlichen kleinen Speicheldrüsen identifiziert werden, dies galt für beide Schnittbildverfahren. Als hilfreiche anatomi-sche Landmarken konnten der äußere Gehörgang, der M. masseter, der M. pterygo-ideus medialis und der Bulbus oculi herangezogen werden. Die medianen Dichtewer-te lagen für die Glandula parotis, die Glandula mandibularis und die Glandula zygo-matica bei 65 HU, 62 HU und 57 HU. Die Parotis war überwiegend dezent hyperin-tens zur Muskulatur und hypointens zum Fett. Die Mandibularis, Zygomatica, und Glandula buccalis ventralis stellten sich hauptsächlich hyperintens zur Muskulatur und hypointens zu Fettgewebe dar. Dieses Signalverhalten war für T1W, T2W und T2W SPIR (fettunterdrückt) gewichtete Sequenzen gleich. Die Größe war für beide Gruppen und Modalitäten vergleichbar und lag bei circa 17 x 6 mm (gemessen von lateral nach medial und von dorsal nach ventral) bei der Glandula parotis, 8 x 17 mm bei der Glandula mandibularis, 10 x 7 mm bei der Glandula zygomatica und bei der Glandula buccalis ventralis 3 x 10 mm. Schlussfolgerungen: Landmarken und Aussagen über die Signalintensität bezie-hungsweise Dichte und die Größe der Glandula parotis, Glandula mandibularis, Glandula zygomatica und der Glandula buccalis ventralis konnten erhoben werden. Die mangelhafte Identifizierbarkeit der restlichen kleinen Speicheldrüsen, im Ver-gleich zu den oben genannten, kann vor allem mit dem unzureichenden Weichteil-kontrast zum umliegenden Gewebe im CT und der niedrigen Auflösung des Nieder-feld-MRTs erklärt werden. Neuere MRT-Techniken können detailliertere Bilder er-zeugen und so eine Beschreibung der kleinen Speicheldrüsen ermöglichen<br>Objective: Due to their high resolution and useful contrast resolution, CT and MRI are recommended methods for diagnosing pathological changes of soft tissues such as lesions of the salivary glands. To our knowledge, no studies about the CT or MR anatomy of the feline salivary glands have been published yet. The aim of the study was to define anatomical characteristics of the salivary glands in cross-sectional im-ages and to describe landmarks for a reliable identification. Materials and methods: Two groups of cats where examined. In a prospective trial, 16 cats, euthanized for reasons unrelated to the study, underwent a head CT (1 mm slice thickness) and 0.5 Tesla MRI scans (T2W, T2W SPIR, PDW, T1W). In a retro-spective trial, the CT scans (0.8-1 mm slice thickness) of 25 cats and the MR scans (T2W, T1W, pre- and post-contrast) of 21 cats were used. These scans were per-formed at our clinic between 2005 and 2013. No signs of salivary-gland-related pa-thologies were visible. All images were reviewed with respect to the following criteria: the presence, delineation and size of the salivary glands as well as the signal intensi-ty. Anatomical landmarks surrounding the glands were also recorded. Results: 94.3% of the parotid glands, 90.7% of the mandibular glands and 96.8% of the zygomatic glands could be delineated using CT. With MRI, 94.1% of the parotid Summary 82 glands, 99.2 % of the mandibular glands, 88.9% of the zygomatic glands and 51,4 % of the ventral buccal glands could be identified. In both groups the other small salivary glands could not be visualized neither in CT nor in MRI. Anatomical landmarks such as the external ear canal, the M. masseter, the M. pterygoideus medialis and the Bulbus oculi facilitate the identification. The mean density of the parotid gland, the mandibular gland and the zygomatic gland was 65 HU, 62 HU and 57 HU, respectively. The parotid gland was mainly modestly hyperintense to muscle and hypointense to fat. The mandibular, zygomatic and ven-tral buccal glands were hyperintense to muscle and hypointense to fat. Signal intensi-ties were similar for T1W, T2W and T2W SPIR images. Sizes were comparable for both groups and modalities and measured about 17x6 mm (lateral to medial and dor-sal to ventral) for the parotid gland, 8 x 17 mm for the mandibular gland, 10x7 mm for the zygomatic gland and 3x10 mm for the ventral buccal gland. Conclusions: Landmarks were recorded and data regarding the density/signal in-tensity and the size of the parotid gland, the mandibular gland, the zygomatic gland and the ventral buccal gland could be gathered. The discrepancy between depicting the small glands and the above mentioned glands can be explained mainly by the lack of contrast to the surrounding tissue in CT and the low spatial resolution in low-field MRI. Advanced MRI techniques are expected to produce more detailed images and therefore those techniques could be used to also describe the small salivary glands
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Karlsson, Terese. "Improvements within patient experience during MRI." Thesis, KTH, Människa och Kommunikation, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209939.
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MRI is one of the biggest and most growing imaging techniques. Even though itis one of the most harmless technologies a big portion of the patients experienceanxiety during the exam. By improving the patient experience unnecessary psychologicalstress for the patient can be prevented, the patient movement wouldthen decrease and therefore the imaging can be improved without changing thetechnique. Participant observations at four dierent MRI departments werecompleted with six interviews with radiographers and technical MRI personnelin order to get insight in the work around an MRI exam and the problemsthat patients experience. The data collection resulted in three improvementareas: the atmosphere of the waiting room, the atmosphere of the MRI roomand the headset used by the patient during the MRI exam. These improvementareas were paired up with solution suggestions which were then controlled andcommented by one MRI specialist, one MRI developer and one radiographer tovalidate the suggestions. The conclusion was that there is already much doneto improve the environment in the MRI room, even though more can be done.The waiting room, on the other hand ,has not been an object for studies orfor improvements before. Therefore more calculation about how big of a protit could be, to improving the atmosphere in the waiting room, should be doneso one knows how much resources one can be put into that improvement area.Lastly there are potential solutions for how to create a much better headset butbecause the generated solutions in this area are so technically challenging moreresearch has to be done before it can be realised.<br>MR är en av de största och mest växande medicinsk bildgivande teknikerna som finns. Även om tekniken är helt ofarlig är det många patienter som lider av ångest kopplad till undersökningen. Genom att förbättra patientens upplevelse kan man förbygga den ångesten, då kommer också patienten kunna ligga mera still under undersökningen och därför kommer bilderna kunna förbättras utan att ändra tekniken.Datainsamlingen bestod av deltagande observationer på fyra olika röntgenavdelningar tillsammans med sex stycken intervjuer med både röntgensköterskor och personal som jobbar med MR-tekniken. Detta för att få en inblick i jobbet runt en MR undersökning och problemtiken som patienterna upplever. Datainsamlingen resulterade i tre olika förbättringsområden: väntrummet, undersökningsrummet och headsetet som patienten använder under MR-undersökningen. Dessa förbättringsområden parades ihop med förbättringsförs-lag och validerades sedan med en MR speciallist, en utvecklare och en röntgensköterska.Slutsatsen var att det idag görs mycket för att förbättre miljön i undersökningsrummet, även om mycket mer kan göras. Väntrummet, och andra sidan, har inte varit föremål för varken studier eller förbättringar och därför behöver uträkningar göras på hur stor vinst det skulle vara med en förbättrad miljö där för att veta hur mycket resurser som kan läggas på det. Till sist kan det konstateras att det finns potentiella lösningar för hur ett bättre headset skulle kunna skapas, men eftersom de förslagen som genererats i den här studien är så tekniskt avancerade behövs mer forskning för att kunna realisera lösningarna.
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Lustig, Michael. "Sparse MRI /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Mccrea, Gavin. "Mrs Engels." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/48694/.
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The creative component of the thesis consists of a novel entitled Mrs Engels. Mrs Engels is a first-person narrative from the perspective of Lizzie Burns, the Irish lover of the Communist leader Friedrich Engels. The action of the novel is focused on the years 1870-72 when Lizzie and Friedrich move from Manchester to London in order to be close to the Marx’s and the active international Communist scene there. The critical component consists of an essay entitled ‘Illusions of Truth’. ‘Illusions of Truth’ is a meditation on some of the questions raised when we speak of the category of ‘historical fiction’. It is a response to the fact that, often, discussions of historical fiction view ‘the past’ as textual and therefore to some degree unknowable, while taking for granted the knowability of ‘the present’. In other words, in order to assert the textuality of the past, many discussions of historical fiction juxtapose it to an immediately knowable present, sometimes called ‘direct’ or ‘present experience’. But is it true that the present is a more solid, knowable form of human experience than the past? Is direct engagement with reality even possible? Does the present exist at all, except as an historical fiction? The essay uses the theory of Michel Foucault, specifically his ‘archaeological’ and ‘genealogical’ approaches to history, as lenses through which to examine these questions. Grouping its analyses around the larger themes of time, space and truth, it considers whether anything in human experience can, in fact, be present and non-historical (and therefore entirely knowable and true). Can conscious human experience be anything other than historical and fictional? If indeed it cannot, is ‘historical fiction’ as a separate literary classification sustainable?
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Bonhorst, Nicole. "Temperaturveränderungen bei Säuglingen und Kleinkindern während einer 3T-MRT-Untersuchung in Sedierung." Doctoral thesis, Universitätsbibliothek Leipzig, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-77405.
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Bei einer MRT in Sedierung steht der potentielle Wärmeverlust über die Körperoberfläche einem Temperaturanstieg durch die Absorption von Energie aus dem Hochfrequenzfeld der Sendespule gegenüber. Bei Schädel-MRT-Untersuchungen in bereits vorliegenden Studien (1,5T, 3T) konnte mittels Ohrtemperaturmessung vor und nach der MRT ein Temperaturanstieg von 0,5 ° C bei Säuglingen und Kleinkindern gemessen werden. In der vorliegenden Arbeit sollte untersucht werden, ob bei 3T-MRT-Untersuchungen unterschiedlicher Körperregionen und Dauer in Propofol-Sedierung bei Säuglingen und Kleinkindern eine Zu- oder Abnahme der Körpertemperatur stattfi ndet und ob eine kontinuierliche Temperaturüberwachung auf der Haut eine verlässliche Messmethode ist. In der klinischen Observationsstudie wurden 50 Kinder im Alter bis zu 6 Jahren eingeschlossen und eine 3T-MRT in Propofol-Sedierung durchgeführt (ASA 1 und 2). Erstmalig erfolgte die Temperaturüberwachung kontinuierlich axillär mit einem Fiber TEMPTM Reusable Fiber-optic Surface Temperature Sensor (Invivo, Orlando/Florida, USA). Zur Kontrolle wurde die Ohrtemperatur vor und nach der MRT mit einem Infrarotthermometer First Temp Genius (Covidien Deutschland GmbH) gemessen und vegetative Reaktionen dokumentiert. Es zeigte sich ein mit der Literatur vergleichbarer signi fikanter mittlerer Temperaturanstieg auf der Haut von 36,4 ± 0,5 °C auf 36,9 ± 0,5 ° C auch bei unterschiedlichen Untersuchungszeiten und -regionen. Die nachgewiesene Erwärmung ist bei gesunden Kindern nur von geringer klinischer Relevanz. Es sind bei einer 3T-MRT-Untersuchung weder eine verstärkte Wärmezufuhr noch eine Kühlung notwendig, um Säuglinge und Kleinkinder normotherm zu halten. Ist bei speziellen Indikationen eine kontinuierliche Temperaturüberwachung notwendig, liefert ein faseroptischer Temperatursensor korrekte Daten<br>In case of MRI in infants and children during propofol sedation the potential loss of body temperature confronts the temperature increase due to the absorption of energy from the high-frequency field of the transmitter coil. Therefore the physician must be aware of both effects when caring for sedated children. Objective of the present study is the effect of 3T-MRI of different body regions and scan duration on body temperature measured continuously in propofol sedated infants and children, which was not performed previously. 50 children in the age up to 6 years have been included in the observational study carried out between October 2008 and March 2009 at the Department of Pediatric Radiology, University of Leipzig. They underwent an elective 3T-MRI while sedated with propofol. The temperature monitoring has been carried out continuously axillary with a new fiber-optic sensor. For control, the tympanic temperature has been measured prior and after the MRI-examination with an infrared thermometer. A significant (p<0,05) medial temperature increase from 36,4 ± 0,5 °C to 36,9 ± 0,5 °C was evident measured axillarly with the fiber-optic sensor. Heart rate and oxygen saturation were stable throughout the MRI scan. In healthy children, the measured increase of temperature during 3T-MRI is only of minor clinical relevance. If a continuous temperature monitoring is necessary in cases with special indications e.g. critical ill children, a fiber-optical temperature sensor generates reliable data
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Sünkel, Henning. "Prognostischer Wert der kardialen Magnetresonanztomographie bei Patienten mit ST-Hebungsinfarkt - Analyse der Parameter linksventrikuläre Ejektionsfraktion, Infarktgröße, mikrovaskuläre Obstruktion und myokardialer „Salvage“ in einer multizentrischen Studie." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-172834.
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Die kardiale Magnetresonanztomographie (MRT) ermöglicht nach einem akuten Myokardinfarkt (AMI) die Visualisierung und Quantifizierung der Myokardschädigung anhand verschiedener Parameter wie Ejektionsfraktion (EF), Infarktgröße, Mikrovaskuläre Obstruktion (MO) und „Myocardial Salvage Index“ (MSI). Anhand dieser MRT-Marker kann das Risiko für kardiovaskuläre Komplikationen eingeschätzt werden, was für die Weiterversorgung des Patienten sowie für die kardiologische Forschung von großem Interesse ist.
In dieser Arbeit wurde die prognostische Relevanz der MRT-Parameter erstmals in einer großen, multizentrischen Studie untersucht. Zudem sollte unter den vier genannten MRT-Markern derjenige mit der größten prognostischen Aussagekraft ermittelt werden. Dazu wurden 795 Patienten aus der AIDA STEMI Studie einer MRT unterzogen und dann zwölf Monate lang im Hinblick auf den kombinierten Endpunkt „Major Adverse Cardiac Events“ (MACE; bestehend aus Tod, Reinfarkt und Klinikaufnahme wegen Herzinsuffizienz) nachbeobachtet.
Die Ergebnisse belegen, dass die genannten MRT-Parameter prognostisch relevant sind und insbesondere die MO und die Infarktgröße einen Einfluss auf die Prognose ausüben, welcher über den Wert etablierter klinischer Risikomarker hinausgeht. Herausragende Bedeutung kommt dabei der MO zu, welche nach multivariater Analyse der potenteste MRT-Prädiktor für kardiovaskuläre Ereignisse ist.
Somit sollten die MRT-Parameter in kommenden kardiologischen Studien als Surrogatmarker für klinische Endpunkte berücksichtigt werden. Zudem könnten sie für den klinischen Alltag die Möglichkeit bieten, die Patientenversorgung enger an die individuelle Prognose anzupassen.
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Dvořáková, Lenka. "Kvantifikace T1 pro preklinické MRI." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220864.
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T1 mapping of myocardial tissue is important for diagnostics of myocardial fibrosis. Cardiac magnetic resonance imaging of small animals is challenging due to high heart and respiratory rates. Pulse sequences for T1 mapping are proposed in this thesis based on inversion recovery FLASH and Intragate FLASH. The sequence IR FLASH was compared to the reference sequence RARE on a static phantom. Both sequences were applied for measuring the myocardium of a rat. For T1 quantification a software in Matlab was developed. Using this software, T1 maps of rat myocardium were calculated.
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Ellis, Lucy C. J. "Human and rat multidrug resistance-associated proteins (MRP/Mrp)." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=128325.
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The multidrug resistance associated proteins (MRP(human)Mrp (rat) are ATP-dependent transporters responsible for the efflux of a wide range of substrates, including endogenous compounds e.g. bilirubin, drug metabolites e.g. paracetamol glucuronide and fluorescent dyes e.g. 5 (and 6)-carboxy-2’,7’-dichlorofluorescein (CDF). Mrp1-6 (<i>abccl-6)</i> are expressed in rat liver, with Mrp2 being expressed at the highest level. Isolation of hepatocytes by <i>in situ</i> collagenase perfusion causes bile canalicular disruption and internalisation of Mrp2. Cells cultured in a sandwich configuration of Matrigel or collagen (Type 1) showed bile canalicular reformation at different days in cell culture, depending on the extracellular matrix and time of overlay. We have developed a method for quantifying Mrp-mediated efflux in hepatocytes cultured in a sandwich configuration of collagen (Type 1). This method is unique in its ability to distinguish between sinusoidal efflux, canalicular efflux and diffusion in intact hepatocytes. Alternative <i>in vitro</i> models of Mrp2-mediated efflux include the vesicular (direct and indirect methods) and the ATPase assays. We have used these assays to identify atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin and simvastatin as substrates of human and rat MRP2/Mrp2. A close correlation was seen between the kinetic parameters of transport of the Mrp2 substrate; CDF determined in sandwich cultured rat hepatocytes using the method above (Km = 3.5 – 9.9 μM), vesicle preparations (Km = 37.9 μM) and membrane preparations (Km = 18.7 μM). We also present data to implicate the nuclear receptors, PXR, CAR and FXR in the regulation of <i>abcc2</i> and <i>abcc3</i> and PXR and CAR in <i>abcc1</i> gene regulation. <i>Abcc2 </i>and abcc5<i> </i>are also up-regulated in response to a toxic insult to the cell, probably via Nrf2 activation, suggesting a role in cell defence.
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Torkul, Orhan. "A comparison of MRP/GT and MRP/JS scheduling." Thesis, Cranfield University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333138.
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Hellström, Karlsson Rebecca, and Tobias Peterson. "Extracting Cardiac and Respiratory Self-Gating Signals from Magnetic Resonance Imaging Data." Thesis, KTH, Skolan för teknik och hälsa (STH), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171570.
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Motion artefacts due to cardiac and respiratory motion present a daily challenge in cardiac Magnetic Resonance Imaging (MRI), and many different motion correction procedures are used in clinical routine imaging. To reduce motion artefacts further, patients are required to hold their breath during parts of the data acquisition, which is physically straining – especially when done repetitively. Self-Gating (SG) is a method that extracts cardiac and respiratory motion information from the MRI data in the form of signals, called SG signals, and uses them to divide the data into the specific cardiac and respiratory phases it was acquired from. This method both avoids motion artefacts and allow for free-breathing acquisition. This project’s goal was to find a method for extracting cardiac and respiratory SG signals from MRI data. The data was acquired with a golden angle radial acquisition method for 3-dimensional (3D) scans. Extraction of the raw signal was tested for both raw k-space data and high temporal resolution image series, where the images were reconstructed using a sliding window reconstruction. Filters were then applied to isolate the cardiac and respiratory information, to create separate cardiac and respiratory SG signals. Thereafter trigger points marking the beginning of the cardiac and respiratory cycles were generated. The trigger points were compared against ECG and respiratory trigger points provided by the MR scanner. The conclusion was that the SG signals based on k-space data was functional on the scans from the evaluated subjects and the most effective choice of the two options, but image based SG signals may prove to be functional after further studies.<br>Rörelseartefakter på grund av hjärt- och respirationsrörelser är idag vardagliga utmaningar inom magnetresonanstomografi (MR) av hjärtat, och många olika metoder används för att eliminera rörelseartefakterna. Patienterna behöver dessutom hålla andan under delar av dataupptagningen, vilket är fysiskt ansträngande – speciellt när det sker upprepade gånger. Self-Gating (SG) är en metod som extraherar information hjärt- och respirationsrytm från MR-datan i form av signaler, kallade SG signaler, och använder dem för att dela in datan i de specifika hjärt- respektive respirationsfaser som var när datan upptogs. Denna metod både undviker rörelseartefakter och tillåter fri andning under dataupptagningen. Målet med det här projektet var att hitta en metod för att extrahera SG signaler för hjärt- och respirationsrytm från MR-data. Datan samlades in med en golden angle radial-upptagning för 3- dimensionella (3D) scanningar. Extraheringen av den råa signalen testades på både rå k-space data och på bildserier av 3D-bilder med hög tidsupplösning, där bilderna var rekonstruerade med en sliding window rekonstruktion. Därefter applicerades filter för att isolera hjärt- och respirationsinformationen, för att få separata SG signaler med endast hjärt- respektive respirationsrytmer. Till slut genererades triggerpunkter för att markera början av hjärt- respektive respirationscyklerna. Dessa jämfördes med triggerpunkter uppmätta med EKG och andningskudde i magnetkameran. Slutsatsen för projektet var att SG signalerna som baserades på k-space data var funktionell för de scanningar som testades och det mest effektiva alternativet, men SG signalerna som baserades på bilder kan visa sig fungera efter mer studier.