Dissertations / Theses on the topic 'Functional UltraSound'
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Rau, Richard [Verfasser]. "Functional Ultrasound Imaging of the Avian Brain / Richard Rau." Konstanz : Bibliothek der Universität Konstanz, 2018. http://d-nb.info/1163537047/34.
Full textImbault, Marion. "Quantitative and functional ultrafast ultrasound imaging of the human brain." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC158/document.
Full textThe objective of this thesis was to explore the potential of human brain ultrasound imaging. Anatomy, blood flow and soft tissue stiffness have already been studied with ultrafast ultrasound imaging in humans and validated in several organs, such as, the breast and liver but not yet on the adult brain. The main limitation of transcranial ultrasound imaging is today the very strong skull-induced aberration artefact. Indeed, the bone, due to its composition, does not allow for ultrasound propagation as elsewhere in the human body. Therefore, this thesis was focused on the development of ultrafast ultrasound imaging for the evaluation of soft tissue stiffness and neurofunctional imaging in the adult human brain, during brain surgery to bypass the problem of skull aberration, and on an aberration correction technique for transcranial ultrasound imaging.We first provided several evidence of the benefit of using shear wave elastography during brain surgery. We also presented our new technique for 3D shear wave elastography using a matrix array in order to be able to overcome the limitations of 2D imaging and in particular to reduce the operator dependence.In a second phase, we demonstrated the capability of ultrasound to identify, map and differentiate in depth cortical regions of activation in response to a stimulus, both in awake patients and in anaesthetized patients. We have demonstrated that ultrasound neurofunctional imaging has the potential to become a comprehensive modality of neuroimaging with major benefits for intraoperative use. In a third part, we developed a new sound speed estimation (SSE) technique, based on a three-step technique that estimates the sound speed accurately corresponding to the illuminated medium. This technique was tested in ultrasound phantoms and in vivo in patient’s liver. In both cases, our method was able to find the sound speed corresponding to the medium. We demonstrated that SSE was related to the fat fraction. This analysis led to the conclusion that SSE was able to distinguish a healthy liver from a diseased liver with both biopsy and MRI as gold standard. Combined with the use of the Wood’s formula, we were even able to access a fat fraction measured by non-invasive ultrasound. Finally, by combining the phase, the amplitude and the sound speed estimation, we have developed a new aberration correction algorithm to perform transcranial ultrasound imaging. By performing numerical simulations, we obtained images that faithfully represented the medium (lateral position and depth) and characterized by one resolution and one contrast similar to those obtained with a punctual source in the medium
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.
Full textSince 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
Blomley, Martin John Kjolsen. "Ultrasound contrast agents as a tool for quantitative-functional imaging." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417930.
Full textGesnik, Marc. "Imagerie fonctionnelle par ultrasons de la rétine et des fonctions visuelles cérébrales." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLET011/document.
Full textThis thesis focuses on recent improvements in the functional ultrasound imaging (fUS) technique and their applications in the field of ophthalmology. Within the framework of a synergetic project blending waves physics, medical imaging, neuroscience and ophthalmology, fUS was shown to be capable of imaging and studying the visual system of healthy and diseased animals for the purpose of preclinical studies. To tackle these issues, constant upgrades in the fUS technique had to support the preclinical studies.An experimental set-up was built to image the visual pathway in three dimensions with fUS. Using a new imaging facility, fUS was proven to be feasible in real time and at high ultrasound frequencies such as 30 MHz. Interleaved sampling had to be implemented in that case. Furthermore, the a priori knowledge of the vascular cerebral architecture and the Doppler Effect were exploited to spectrally decompose cerebral blood flux and vessels according to their velocities and orientations.Leveraging these improvements, functional ultrasound imaging of rats and non-human primates was performed. Primate retina was imaged with Power Doppler, but proved to be too mobile to be functionally imaged. However, fUS has been performed on rat retina after 30 MHz fUS imaging had been implemented. The rat visual pathway has then been characterised with fUS. Some of its known features where highlighted such as its retinotopic organisation or the time response differences between some of its structures. The same set-up has been leveraged to map the cerebral activity of animal that underwent visual restauration therapies. These tools were then used to map cerebral activity in anesthetized and awake and behaving monkeys. Unique blood volume variations due to unique mistakes were detected. These tools were finally applied to two preclinical trials on a depressive state of the brain vascular contractility. Blood volume and blood velocity changes were highlighted throughout an acute and a chronical study
Upadhyaya, Swati. "Decreasing Error in Functional Hip Joint Center Calculation using Ultrasound Imaging." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26125.
Full textSatta, Elena. "The modulation of buckwheat flour techno-functional properties by ultrasound treatment." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textBloch, Susannah Helen. "Ultrasound functional analysis of breast tumours using a microbubble contrast agent." Thesis, Institute of Cancer Research (University Of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399740.
Full textBimbard, Célian. "Accessing the encoding of sounds in the auditory cortex using functional UltraSound." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEE054.
Full textThe world teems with complex sounds that animals have to interpret in order to survive. To do so, their brain must represent the richness of the sounds' acoustic structure, from simple to high-order features. Understanding how it does it, however, remains filled with challenges. In this thesis, these questions were explored through a new technical prism, namely functional UltraSound imaging (fUSi). First, fUSi was used to investigate with a high fidelity the topographical organization of the auditory system, as well as its connectivity with other brain areas. Second, it provided fundamental clues for our understanding of how natural sounds are encoded in the auditory cortex, and hints at the human particularities for speech processing. Last, it gave us access to non-continuous topographical encoding, with the example of spatial localization. Through these three aspects, we exposed the different spatially organized modules of processing that overlap within a single brain area
O'Sullivan, Jonathan James. "Applications of ultrasound for the functional modification of proteins and submicron emulsion fabrication." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6086/.
Full textErrico, Claudia. "Ultrasound sensitive agents for transcranial functional imaging, super-resolution microscopy and drug delivery." Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC013.
Full textThis thesis focuses on two main branches of the application of ultrasound contrast agents: microbubbles-aided ultrafast ultrasound imaging of the brain and ultrasound-triggered drug delivery for cancer therapy. At first, gas-filled microbubbles have been used to retrieve the brain activation through the skull in large animais. With this approach we have been able to non-invasively reconstruct the cerebral network of the brain, as well as retrieve its hemodynamic response to specific evoked tasks with high spatiotemporal resolution. The validation of this novel functional ultrasound (fUS) imaging approach was facilitated by the high sensitivity of the ultrasensitive Doppler technique able to detect subtle hemodynamic changes due to the neurovascular coupling. These resuits suggested that combining microbubbles injections with ultrafast imaging may help to fully compensate for the attenuation from the skull. Indeed, by combining both, we preserved resolution and increased penetration depth. The injection of ultrasound contrast agents has also lead to outstanding resuits in ultrafast ultrasound imaging by breaking the diffraction barrier and move beyond the half-wavelength limit in resolution. We have demonstrated that cerebral microvessels of 9pm in diameter can me distinguished via ultrafast ultrasound localization microscopy (uULM). Millions of blinking sources were localized in space and in time in few seconds in a higher dimensional space, leading to super-resolved images (microbubble density map) of the whole rat brain with a spatial resolution of À/10. Moreover, a displacement vector allowed microbubbles-tracking within frames yielding to in-plane velocity measurements retrieving a large dynamic of cerebral blood velocities. Next, we have exploited how we can spatiotemporally control the vaporization of composite perfluorocarbon (PFC) microdroplets when their activation is triggered by short ultrasound pulses. The concept 'chemistry in-situ' is introduced as we have been able to control a spontaneous chemical reaction in-vitro. Moreover, a new microfluidic device in glass has been proposed to robustly produce monodisperse droplets for future in-vivo applications of the chemistry in situ. This new device presents 128-parallel generators with two pressurized rivers. Eventually, new ultrafast ultrasound monitoring sequences have been developed in order to control and monitor the release of composite droplets
ye, Yubin. "Effect of High Intensity Ultrasound on Crystallization Behavior and Functional Properties of Lipids." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4281.
Full textStevenson, Gordon N. "Toward functional imaging of the placenta." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1d459989-7e03-4cfe-b1b9-98833e5db854.
Full textBrown, Phillip G. M. "2D ultrasound elastography as a functional measure of healing of the Achilles tendon in vivo." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e2d0a97e-d557-4b5a-869a-36cbd33b9994.
Full textBakhtiari, Nejad Marjan. "Dynamics of Multi-functional Acoustic Holograms in Contactless Ultrasonic Energy Transfer Systems." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/102414.
Full textDoctor of Philosophy
This dissertation presents several techniques to enhance the wireless transfer of ultrasonic energy in which the sound wave is generated by an acoustic source or transmitter, transferred through an acoustic medium such as water or human tissue to a sensor or receiver. The receiver transducer then converts the vibrational energy into electricity and delivers to an electrical load in which the electrical power output from the system can be determined. The first enhancement technique presented in this dissertation is using a pre-designed and simple structured plate called an acoustic hologram in conjunction with a transmitter transducer to arbitrarily pattern and shape ultrasound fields at a particular distance from the hologram mounted on the transmitter. The desired wavefront such as single or multi-focal pressure fields or an arbitrary image such as a VT image pattern can simply be encoded in the thickness profile of this hologram plate by removing some of the hologram material based on the desired shape. When the sound wave from the transmitter passes this structured plate, it is locally delayed in proportion to the hologram thickness due to the different speed of sound in the hologram material compared to water. In this dissertation, various hologram types are designed numerically to implement in the ultrasonic power transfer (UPT) systems for powering receivers located at the predetermined focal points more significantly and finally, their functionality and performances are verified in several experiments. Current UPT systems suffer from significant acoustic losses through the transmission from a transmitter to an acoustic medium and then to a receiver due to the different acoustic impedance (defined as the product of density and sound speed) between the medium and transducers material, which reflects most of the incident pressure wave at the boundary layers. The second enhancement technology addressed in this dissertation is using intermediate materials, called acoustic impedance matching layers, bonded to the front side of the transmitter and receiver face to alleviate the acoustic impedance mismatch. Experiments are performed to identify the input acoustic pressure from a transmitter to a receiver. Using a two-layer matching structure, significant enhancements are observed in terms of the receiver's electrical power output. A design platform is also developed that can facilitate the construction of high-fidelity acoustically matched transducers, that is, the material layers' selection and determination of their thicknesses. Furthermore, this dissertation presents a numerical analysis for the dynamical motions of a microbubble exposed to a high-intensity focused ultrasound (HIFU) field, which entails the problem of several biomedical ultrasound applications such as microbubble-mediated ultrasound therapy or targeted drug delivery. Finally, an enhancement technique involving the design and use of acoustic holograms in microfluidic channels is addressed which opens the door of acoustic patterning in particle and cell sorting for medical ultrasound systems.
Cazzanelli, Silvia. "Functional ultrasound (fUS) imaging of brain functional connectivity alterations in a mouse model of neuropathic pain : impact of nociceptive symptoms and associated comorbidities." Electronic Thesis or Diss., Université Paris sciences et lettres, 2024. http://www.theses.fr/2024UPSLS010.
Full textNeuropathic pain is an abnormal pain sensation that persists longer than the temporal course of natural healing. It interferes with the patient’s quality of life and leads to several comorbidities, such as anxiety and depression. It has been suggested that chronic pain may result from abnormal and maladaptive neuronal plasticity in the structures known to be involved in pain perception (Bliss et al. 2016). This means that nerve injury would trigger long-term potentiation of synaptic transmission in pain-related areas (Zhuo et al. 2014). Since these regions are also involved in the emotional aspects of pain, our hypothesis is that the aforementioned maladaptive plasticity in these brain areas could constitute a key mechanism for the development of comorbidities such as anxiety and depression.My PhD aimed at testing this working hypothesis, through the study of brain resting state functional connectivity (FC) using functional ultrasound imaging (fUS) in a mouse model of neuropathic pain. FUS is a relatively recent neuroimaging technique that enabled numerous advances in neuroscience, thanks to its high spatio-temporal resolution, its sensitivity, but also its adaptability, allowing studies in anesthetized or awake animals.In a first study, I developed an experimental protocol allowing the brains of awake mice to be imaged in a reproducible manner and with minimal stress and movement artifacts and was also involved in the development of a new algorithm for the analysis of the signals generated by these acquisitions. As this first approach was carried out with a moving linear probe which does not allow the entire brain to be visualized, in a second study, I participated in the development of a new compiled and motorized probe technology.Building on these technological developments, I then used these new approaches to test my neurobiological hypothesis. I undertook two parallel studies in animals anesthetized for one and awake for the second, in which we studied the temporal link between alterations in cerebral FC and the development of neuropathic pain and/or associated comorbidities. To do this, we measured the resting-state functional connectivity (FC) in anesthetized and in awake head-fixed mice, at three time points: I) 2 weeks after induction of neuropathic pain (cuff around the sciatic nerve), II) at 8 weeks post-induction during the emergence of anxiety (8W) and III) at 12 weeks post-induction during the emergence of depression. This longitudinal follow-up has been conducted concurrently on a control group.Our results show significant changes in FC in major pain-related brain regions in accordance with the development of neuropathic pain symptoms. These findings suggest that the pain network undergoes maladaptive plasticity following nerve injury which could contribute to pain chronification. Moreover, the time course of these connectivity alterations between regions of the pain network could be correlated with the subsequent apparition of associated comorbidities
Tang, Mei-yee, and 鄧美宜. "Medical imaging: applications of functional magnetic resonance imaging and the development of a magnetic resonancecompatible ultrasound system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37897688.
Full textNouhoum, Mohamed Nabhane. "Neuro-navigation automatique pour la neuro-imagerie fonctionnelle ultrasonore." Electronic Thesis or Diss., Université Paris sciences et lettres, 2021. http://www.theses.fr/2021UPSLS047.
Full textUltrafast ultrasound imaging is a recent method based on transmission of plane waves which enables the visualization of biological media with high spatio-temporal resolution. When applied to Doppler imaging, it enables detection of blood flow with very high sensitivity compared to conventional ultrasound Doppler usually limited to high blood flow imaging in cardiology. This advances have rendered functional ultrasound (fUS) imaging a valuable neuroimaging modality capable of mapping cerebral vascular networks, but also to indirectly capture neuronal activity with high sensitivity thanks to the neurovascular coupling. However, the expansion of fUS imaging is still limited by the difficulty to identify cerebral structures during experiments based solely on the Doppler images and the shape of the vessels, which complicates the positioning of the ultrasound probe and the data analysis of the data. It is therefore crucial to set up tools dedicated to functional ultrasound imaging in the same way as functional imaging by MRI, which remains the reference modality.This thesis focuses on the development and validation of cerebral GPS, an automatic neuro-navigation tool based on ultrasensitive Doppler vascular footprint of mice and rats. Initially, a vascular anatomical template was built and then registered on familiar atlases (Allen Atlas for the mouse and the SIGMA atlas for the rat) thus allowing the creation of a vascular atlas that can serve as a reference during fUS imaging sessions to align experimental data and provide an anatomical context. The accuracy of the vascular registration was quantified from the super-resolved vascular images obtained with ultrasound localization microscopy.Secondly, the neuro-informatic pipeline has been developed and integrated into a new generation of neuroimaging devices to perform online navigation. We then demonstrated the capability of the system to position itself automatically over chosen anatomical structures and to obtain corresponding functional activation maps even in complex oblique planes. Additionally, we show that the system can be used to acquire and estimate functional connectivity matrices automatically.To go further we explored the potential of vascular GPS to automatically guide intracerebral injections into deep structures. Encouraging results confirmed by fluorescence microscopy images were obtained after injection of a neuronal tracer into the thalamic nucleus. Still on an exploratory basis, we were interested in the reconstruction of structural anatomical images of the brain in addition to the vascular images generally reconstructed in order to assess the echogenicity of a few brain areas identified using vascular GPS. Finally we carried out a longitudinal study in the framework of memory consolidation in rats.This work provides new neuroimaging tools to strengthen the potential of functional ultrasound imaging and allow neuroanatomists experts and non-expert to carry out standardized, reproducible protocols with more accuracy and involving studies on large cohorts
Chandrasekaran, Vigna Nivetha. "Development and characterisation of starch and polyphenols for functional enhancement in high value food products from lontan vegetables." Thesis, La Réunion, 2020. http://www.theses.fr/2020LARE0023.
Full textRoots and Tuber crops plays an eminent, countless and complex part in feeding the world. These crops have the potential to eradicate poverty and improve food security. Starch is the principal component of roots and tuber crops. The significance of starch as a raw material in both food and non-food industries are increasing. In present study efficiency of ultrasound assisted extraction (UAE) to increase the yield of starch and polyphenols from lontan (Canna and Cassava) crops were analysed along with its influence on the physiochemical properties of extracted compounds. Extraction parameters (Temperature, time, solid: liquid ratio) were optimized through Box Behnken response surface design (BBD). Physiochemical and functional properties of starch and polyphenols were investigated through SEM, swelling and solubility index, oil and water absorption index, Total polyphenol yield, DPPH and ORAC assay. Starch yield obtained from canna and cassava at the optimum extraction conditions (Canna: temperature 40°C, time 10 min, solid: liquid ratio 1:30 g/ml; Cassava: temperature 40°C, time 10 min, solid: liquid ratio 1:25 g/ml) were 19.81% and 16.51% respectively. Obtained starch yield was found to be significantly higher than the yield attained through conventional extraction method without any significant or adverse changes in the physicochemical and functional properties. Total polyphenol yield from canna and cassava rhizome was 1061.72 mg GAE/&100g and 7644.46 mg GAE/&100g respectively. Total polyphenol yield obtained through UAE was found to be significantly higher than conventional method. Antioxidant activity of bioactive compounds analysed through DPPH and ORAC was found to be directly proportional to the attained polyphenol yield. From the obtained results it can be observed that UAE has the efficiency to increase the yield of starch and polyphenols without altering the properties of isolated compounds
Tang, Mei-yee. "Medical imaging : applications of functional magnetic resonance imaging and the development of a magnetic resonance compatible ultrasound system /." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36749710.
Full textBergel, Antoine. "Cerebral vascular patterns associated with theta and gamma rhythms during unrestrained behavior and REM sleep." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC239/document.
Full textTheta rhythm is a prominent oscillatory pattern of EEG strongly associated with active locomotion and REM sleep. While it has been shown to play a crucial role in communication between brain areas and memory processes, there is a lack of extensive data due to the difficulty to image global brain activity during locomotion behavior. In this thesis, I developed an approach that combines local field potential recordings (LFP) and functional ultrasound imaging (fUS) to unrestrained rats. For the first time, I could image the hemodynamic responses associated with theta rhythm in most central nervous system (CNS) structures, with high spatial (100 x 100 x 400 μm) and temporal (200 ms) resolutions. During running and REM sleep, hemodynamic variations in the hippocampus, dorsal thalamus and cortices (S1BF, retrosplenial) correlated strongly with instantaneous theta power, with a delay ranging from 0.7 to 2.0 s after theta peak. Interestingly, mid (55-95 Hz) and high gamma (100-150 Hz) instantaneous power better explained hemodynamic variations than mere theta activity, while low-gamma (30-50 Hz) did not. Hippocampal hyperaemia followed sequentially the trisynaptic circuit (dentate gyrus - CA3 region - CA1 region) and was considerably strengthened as the task progressed. REM sleep revealed brain-wide tonic hyperaemia, together with phasic high-amplitude vascular activation starting in the dorsal thalamus and fading in cortical areas, which we referred to as “vascular surges”. Strong bursts of hippocampal high gamma (100-150 Hz) robustly preceded these surges, while the opposite was not true. Taken together, these results reveals the spatio-temporal dynamics of hemodynamics associated with locomotion and REM sleep and suggest a strong link between theta, high-gamma rhythms and brain-wide vascular activity
Karki, Bishnu. "Use of high-power ultrasound during soy protein production and study of its effect on functional properties of soy protein isolate." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3389112.
Full textWang, Tianshu. "Low-intensity pulsed ultrasound prompts both functional and histologic improvements while upregulating the brain-derived neurotrophic factor expression after sciatic crush injury in rats." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/265198.
Full text新制・課程博士
博士(人間健康科学)
甲第23426号
人健博第93号
新制||人健||6(附属図書館)
京都大学大学院医学研究科人間健康科学系専攻
(主査)教授 山田 重人, 教授 林 悠, 教授 森本 尚樹
学位規則第4条第1項該当
Doctor of Human Health Sciences
Kyoto University
DFAM
Sieu, Lim-Anna. "Exploration des réseaux épileptiques par imagerie ultrasonore et électrophysiologie." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066384/document.
Full textEpilepsies consist in neuronal hyperactivities distributed across the nervous system that need first to be located in order to later decipher the mechanisms of these pathologies. While there are many models of epileptiform hyperactivity, it is more difficult to study spontaneous seizures, which are altered by sedation. In this thesis, I developed an approach that combines electroencephalography (EEG) and functional ultrasound imaging (fUS), on the mobile rat. Thus, on a model of absence epilepsy, I could record simultaneously the occurrence of seizures and the hemodynamic variations, which reflect cellular metabolism. Seizures were unaltered by the recording protocol, compared to rats with EEG alone. Correlations were observed between electric and vascular activities. The thalamus showed areas of hyperperfusion during seizures. The cortex exhibited different correlates in distinct areas, with hyperaemia in somato-sensory areas, occasionally associated with a decrease in perfusion in adjacent tissue. The sensitivity of fUS, which could resolve blood changes from single occurrences, revealed that series of spike-wave discharges recorded from an EEG electrode were not always associated with vascular hyperactivity in the same region. Thus, this approach can delimit the contour of areas presenting vascular activity during seizures and shows a partial dichotomy between the electric and vascular components of seizures
RACIOPPO, ANGELA. "Evaluation of the effects of alternative physical approach on the metabolism and functional traits of useful microorganisms." Doctoral thesis, Università di Foggia, 2018. http://hdl.handle.net/11369/369201.
Full textScientific background: Probiotics in foods could lead to significant changes in food flavor and rheology, due to their active metabolism. A possible way to overcome this problem is the attenuation of probiotics through a physical or chemical method. Some authors studied homogenization as a way to attenuate/modulate the metabolism of starter cultures in dairy products (Lanciotti et al., 2004, 2006, 2007); in this project I have used a new emerging technology, the ultrasounds. (i) A screening of the ultrasound (US) (power/duration) on different probiotic microorganisms was perfomed, and were studied the probiotic and technological characteristics after US-exposure. (ii) The effects of US on the release of intracellular components, was investigate. (iii) The interaction of attenuated strains with gut microbiota was evaluated, using in vitro batch culture fermentation. Open questions: (i) Few data are available on effects of US on probiotics and technological characteristics of probiotic strains; (ii) few data are available on the effect of attenuation with ultrasound on the sub-lethal injury; (iii) no data are available on the interaction of attenuated strains with gut microbiota. Aims: (i) Choice of the best combination of ultrasound to avoid post-acidification without affecting the viability of the strains, and study of the probiotic and technological characteristics to evaluate if attenuation could change them; (ii) study the release of intracellular components (nucleic acids and proteins) after the application of ultrasound; and (iii) evaluation the effects of attenuated strains on gut microbiota. Planning of the research: In the first part three different genera of probiotics were used: Lactobacillus, Bifidobacterium, Propionibacterium. The strains were treated with ultrasound and studied for technological and probiotic characteristics. In the second part, the effects of US on the release of intracellular components, was investigated. The strains were studied after physical treatment to assess the release of intra-cellular constituents (nucleic acids, proteins) and injury of the membrane. In the last part, the interaction of attenuated strains with gut microbiota, was studied. This study was carried out at University of Roehampton (UK). Materials and Methods: (i) Technological traits: acidification in lab medium, growth at different temperatures, pHs and salt content; probiotic traits: antibiotic-resistance, survival at pH 2.5 and in the presence of 0.3% bile salt, hydrophobicity, and biofilm formation. (ii) Injury characterization was evaluated by leakage of UV-absorbing substances. (iii) The interaction of attenuated strains with gut microbiota was evaluated, using in vitro batch culture fermentation. Results: (i) The best combinations to avoid post-acidification were the following: power, 60%; time, 6 min; pulse, 2 s for Lactobacillus and Bifidobacterium, 40%, 8 min P. jensenii; 60%, 4 min P. freudenreichii subsp. freudenreichii. US did not affect viability at 45 °C or at pH 9, but it determined a decrease of microbial growth to pH 4 (lactobacilli and bifidobacteria). However, the US did not affect the GI of propionibacteria. The effect of attenuation could be enhanced by the storage under refrigeration. US-treatment did not affect most of the technological traits, but generally caused an increase of susceptibility to some antibiotics. Concerning probiotic traits, US caused an increase of hydrophobicity for L. reuteri and P. freudenreichii spp. freudenreichii, after US-exposure. These results were confirmed with adhesion to Caco-2 cells for L. reuteri. US-attenuated L. reuteri experienced a significant increase of hydrophobicity (from 3 to 25%) and a higher adhesion to Caco-2 cells. Moreover, US improved the stability of the biofilm over the time, and this result confirmed the data obtained with hydrophobicity. (ii) The release of nucleic acids and proteins was found, highlighting that cell membrane could be another target physical treatments. (iii) Concerning the effects of US on gut microbiota, the ultrasound didn’t affect the gut microbiota, but in some cases, it could have a positive effect. Significance and Impact of PhD research: A main drawback of probiotics in foods can relate to their active metabolism, some strains of lactic acid bacteria continue to produce lactic acid and cause post-acidification (the decrease of pH within the storage). Therefore, it is important to control their metabolism. A possible way to control the metabolism of probiotic in foods is the attenuation through physical or chemical methods. One of the emerging technologies is ultrasound (US). This approach was used to avoid post-acidification in a commercial rice drink (Bevilacqua et al., 2016). The present PhD thesis contributed to evaluate the effects of attenuation with ultrasound, on some technological and probiotic strains, testing three different genera of probiotic strains. Moreover, this PhD project has investigate the changes that may affect probiotic strains after attenuation; the release of proteins, nucleic acids. Finally, the novelty of this PhD thesis was the study of the effects of attenuated strains on gut microbiota. Future trends: A future perspective could be a focus on the use of US to improve or modulate the adhesion of probiotic strains, considering the increase of hydrophobicity and the higher adhesion to Caco-2-cells. It is important to investigate the effects of other attenuated strains on gut microbiota by modulating the variables of the treatment. Key words: Hydrophobicity, acidification, growth, attenuation, gut-microbiota, proteins, nucleic acid, ultrasound, attenuated microorganisms, probiotics, lactic acid bacteria.
Morelli, Umberto 1978. "Correlação entre avaliação clínica funcional da função esfincteriana e achados da ultrassonografia endoanal em pacientes com doença de Crohn perineal = Correlation between clinical functional assessment of the sphincteric function and endoanal ultrasound findings in perineal Crohn¿s disease." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/310887.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: Introdução: A incidência da doença de Crohn Perineal (DCP) varia entre 20% a 25% nos portadores de doença de Crohn . O padrão-ouro para a investigação da DCP é a avaliação clínica clássica seguida do exame sob anestesia, mas a ultrassonografia endoanal (USEA) e a ressonância nuclear magnética (RNM) da pelve podem ser úteis na pesquisa de abscessos, fistulas e lesões esfincterianas que podem levar à incontinência fecal e perda da qualidade de vida. Objetivo: Correlacionar a avaliação clínica clássica da função esfincteriana por meio do escore de Jorge-Wexner nos pacientes com DCP, comparando com os achados de USEA, através do escore de Starck. Casuística e Método: Vinte e quatro pacientes participaram do estudo, sendo 14 do sexo feminino e média de idade de 40,54 anos. Todos os doentes tinham diagnóstico confirmado de DCP, sendo que 7 (29,16%) também apresentavam acometimento do intestino delgado; 7 (29,16%) do cólon e reto, 2 (8,33%) do intestino delgado, do cólon e reto e 8 pacientes (33,33%) apresentavam DCP como manifestação única da doença. Resultados: Os dois escores apresentaram distribuição normal, com escore de Jorge-Wexner médio de 3,8333 (DP 4,52689) e escore de Starck médio de 9,7500 (DP 2,54097). A análise estatística mostrou não haver correlação entre os dois escores, com um intervalo de confiança de 95%. Conclusão: O escore de Jorge- Wexner apresentou utilidade limitada nessa categoria de pacientes, enquanto a USEA foi ferramenta útil para alcançar melhor correlação com deficiência muscular esfincteriana. No entanto, mais estudos com propostas similares são necessários para aumentar a validade desses achados e para estabelecer se a USEA pode predizer a função esfincteriana e a incontinência fecal antes de procedimento cirúrgico em pacientes com DCP
Abstract: Introduction: The incidence of perianal CD (PCD) is variable between 20% and 25% of patients with CD. The gold standard for assessment of PCD is still the classic clinical examination followed eventually by examination under anesthesia (EUA) but complementary examinations like endoanal ultrasound (EAUS) and magnetic resonance imaging of the pelvis (MRI) were introduced as useful to completely assess the anatomical lesions of the sphincteric muscles caused by fistulas and abscesses. Objective: Verify the adequacy of the classical clinical evaluation to which most of the patients are submitted, in particular regarding the adequacy of assessing the sphincteric function through the Jorge- Wexner score in patients with PCD, comparing it with the findings of EAUS trough a score published by Stark and colleagues. Patients and Methods: Twenty four patients participated to the study, being 16 females and the mean age is 40.54 years old. All patients have an established diagnosis of PCD, being 7 (29,16%) with a diagnosis of CD involving the small bowel, 7 (29,16%) CD involving the colon and rectum, 2 (8,33%) CD involving the small bowel and the colon-rectum, and 8 (33,33%) have a diagnosis of PCD as the only clinical manifestation of CD. Results: The two scores has a normal distribution, with a mean Wexner score of 3.8333 (SD 4,52689) and a mean Starck score of 9,7500 (SD 2,54097). The statistical analysis showed that there is no correlation between the two scores with a confidence interval of 95%. Conclusion: The Jorge-Wexner score had a limited usefulness in this category of patients, whereas EAUS was an useful tool for achieving better correlation with muscle deficiency. This study investigated CD, a very particular and still not fully understood disease, being the perianal disease important feature of CD. However, more studies with similar purpose are needed, in order to improve the validity of these findings, and establish if the EAUS can predict the sphincter function and fecal continence before perianal surgery for CD
Mestrado
Fisiopatologia Cirúrgica
Mestre em Ciências
Abioui, Mourgues Myriam. "Dévelοppement d'un mοdèle préclinique chez la sοuris éveillée et stratégie thrοmbοlytique ciblée pοur l'AVC ischémique." Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC420.
Full textIschemic stroke, caused by the obstruction of a cerebral artery, is one of the leading causes of mortality and disability worldwide. Despite the availability of treatments such as rtPA and endovascular thrombectomy, only a small percentage of patients have access to these. Moreover, despite substantial research efforts, challenges in translating results from animal models to human clinical trials limit the development of new therapies. This thesis presents a novel stroke model in awake mice to improve the translatability of preclinical studies. Through the use of functional ultrasound (fUS) and MRI, this model enables real-time assessment of hemodynamic parameters and functional recovery following ischemia. Additionally, we propose a new tool for evaluating post-stroke brain connectivity, providing insights into brain recovery and treatment response. The efficacy of the stantard thrombolytic treatment, rtPA, was evaluated, and an innovative targeted treatment approach was explored. The results underscore the potential of these multimodal imaging approaches and targeted therapies to enhance ischemic stroke management, opening new avenues for translational research
Sauvage, Jack. "Imagerie ultrasonore ultrarapide 4D par adressage orthogonal du réseau de sonde matricielle : adressage Ligne-Colonne." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS535.
Full textWith the advent of 4D ultrafast imaging at the Physics for Medicine Inserm 1273 laboratory, the ability to acquire in all three dimensions and with a high spatio-temporal resolution has been demonstrated. Several of the most effective 2D ultrafast imaging modalities have been extended to volume imaging (3D ultrasensitive power Doppler, 3D elastography ...). Their dissemination in clinic would greatly benefit to physicians. However the necessary means to implement ultrafast 4D are still too heavy and costly to hope for a transposition in the short or mid-term to the radiology departments. Developing smart strategies to reduce channel number has become a central issue. An original strategy based on the probe architecture consists of orthogonal row and column addressing of the Matrix Probe array, the Row and Column Adressing RCA. It offers a transducer solution perfectly adapted with ultra-fast plane waves imaging. With this approach, the probe can be driven by a single standard ultrasound unit, while maintaining a large aperture. The 2D matrix grid is organized according to N + N orthogonal channels, thus representing a reduction factor of N / 2. This strategy presents an important paradigm shift of imaging by dissociation of the focus pathways in transmission and reception and offers a new compromise in terms of spatio-temporal resolution. During this thesis work, the performances of the RCA associated with the ultra fast 4D imaging are studied for various cases. The principle of 4D ultrafast RCA imaging with orthogonal summation OPW are studied. 3D vector imagery for RCA is developed. A new high frequency RCA probe prototype (15MHz) is presented and tested on a 3D functional brain imaging protocol. Finally, a new modality of 3D imaging of the flux intensity is presented offering a new way of exploitation for the RCA probe
Greaves, Danielle Kathleen. "Désadaptations cardiovasculaires à la microgravité : techniques avancées pour améliorer la mesure et l'évaluation du risque cardiovaculaire induit par les vols spatiaux pour les équipages de longue durée Effects of exercise countermeasure on myocardial contractility measured by 4D speckle tracking during a 21-day head-down bed rest Cardiac and arterial structure and functional changes after four days of dry immersion with and without thigh cuffs Effect of thigh cuff on venous flow redistribution during 4 days in dry immersion." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC433.
Full textObjective: to evaluate functional myocardial contractility after 21 days of head-down bed rest (HDTBR) in sedentary control (CON) or with a resistive vibration exercise (RVE) countermeasure (CM) applied, by using 4D echocardiographic (4D Echo) imaging and speckle tracking strain quantification.Methods: Twelve volunteers were enrolled in a crossover HDTBR design, and 4D Echo was performed in supine position (REST) at BDC-2 and at R+2, and in -6° HDTBR (on day 18), and also during the first and the last minute of the 80° head-up step of Standard Measures tilt test, performed at both BDC-2 and R+2. Radial (Rad-Str), longitudinal (Lg-Str) and twist (Tw-Str) strain were measured by 4D speckle tracking, as well as left ventricle diastolic volume (LVDV) and mass (LVmass).Results: On day 18: in the CON group, LVDV and LVmass were reduced (p<0.05), the Rad-Str decreased (p<0.05) and Tw-Str showed a tendency to increase (p< 0.11), with no changes in Lg-Str. In RVE group, LVDV and LV mass, as well as all the strain parameters remained unchanged.On R+2: in the CON group, LVDV and LVmass were not recovered in all subjects compared to pre-HDTBR (p<0.08), Rad-Str was still decreased (p<0.05), while Tw-Str tended to increase (p<0.09). These parameters remained unchanged in the RVE group.Tilt 80°: Rad-Str and Lg-Str values at 80° tilt were similar post HDT in both groups.Conclusion: 4D Echo and speckle tracking analysis showed that in the CON group, Rad-Str decreased concomitant with LVmass and LVDV with HDTBR, but this observation did not support the hypothesis that this HDTBR induced remodelling or a muscle atrophy. RVE acted to preserve both LVmass, LVDV and contractility during HDTBR, thus proving its effectiveness to this aim. Nevertheless, the significant HDTBR-induced changes observed in the CON group had only a limited effect on the cardiac contractile response as observed during post HDTBR tilt test. The level of contractility at 80° Tilt position was not affected neither by HDTBR nor by RVE CM.Purpose: The objective was to quantify the venous redistribution during a 4-day dry immersion (DI) and evaluate the effect of thigh cuffs.Methods: The study included 9 control (Co) and 9 subjects wearing thigh cuffs during daytime hours (CU). Ultrasound images were collected Pre DI, on the fourth day in the morning (D4 AM) and on the fourth day in the afternoon (D4 PM), to assess the following outcome variables: left ventricle dimension, stroke volume, and ejection fraction (LVD, SV, EF), jugular vein volume (JV), portal vein dimension (PV), middle cerebral vein velocity (MCVv). An additional measure of JV dimension was performed on the first day after having worn the cuffs for two hours (D1 2H).Results: The JV volume increased significantly from Pre to D1 2H in both groups, but increased more in the Co compare to the CU subjects (Co: 0,27+/0.15cm3 to 0.94+/-0;22 cm3;P<0.01 CU: 0,32+/-0.13 cm3 to 0.64+/-0.32 cm3 P<0.042).At D4 AM no difference was found between the two treatment groups for any of the parameters listed above.Stroke volume and EF decreased from Pre (SV:111+/-23cm3 to 93+/-24 cm3 p<0.05; EF:0.66+/-0.07 to 0.62+/-0.07 p<0.05). JV volume was slightly, but significantly increased (Co: 0.47+/-0.22cm3 CU:0.35+/-014cm3 P<0.05), while MCVv and PV remained unchanged from Pre DI. From D4 AM to PM these parameters did not show any significant change.Conclusion: The results confirm that DI induces, during the first 2-3 h, a significant cephalic fluid shift as observed in spaceflight. During this early phase the thigh cuffs reduced the amplitude of the fluid shift towards the head, but after 4 days in DI there was only a slight memory (residual) effect of DI on the jugular volume and no residual effect of thigh cuffs
Farouj, Younes. "Structured anisotropic sparsity priors for non-parametric function estimation." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI123/document.
Full textThe problem of estimating a multivariate function from corrupted observations arises throughout many areas of engineering. For instance, in the particular field of medical signal and image processing, this task has attracted special attention and even triggered new concepts and notions that have found applications in many other fields. This interest is mainly due to the fact that the medical data analysis pipeline is often carried out in challenging conditions, since one has to deal with noise, low contrast and undesirable transformations operated by acquisition systems. On the other hand, the concept of sparsity had a tremendous impact on data reconstruction and restoration in the last two decades. Sparsity stipulates that some signals and images have representations involving only a few non-zero coefficients. The present PhD dissertation introduces new constructions of sparsity priors for wavelets and total variation. These construction harness notions of generalized anisotropy that enables grouping variables into sub-sets having similar behaviour; this behaviour can be related to the regularity of the unknown function, the physical meaning of the variables or the observation model. We use these constructions for non-parametric estimation of multivariate functions. In the case of wavelet thresholding, we show the optimality of the procedure over usual functional spaces before presenting some applications on denoising of image sequence, spectral and hyperspectral data, incompressible flows and ultrasound images. Afterwards, we study the problem of retrieving activity patterns from functional Magnetic Resonance Imaging data without incorporating priors on the timing, durations and atlas-based spatial structure of the activation. We model this challenge as a spatio-temporal deconvolution problem. We propose the corresponding variational formulation and we adapt the generalized forward-backward splitting algorithm to solve it
Sganzella, Daiana. "Ultra-som pulsado de baixa intensidade na regeneração nervosa periférica de ratos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-14022008-091149/.
Full textThe ultrasound is one of the forms therapeutic treatment, no-invasive, that it assists in regeneration peripheral nerve. For in such a way an experimental work was carried through with the objective to verify the effect of the therapy of low intensity pulsed ultrasound after crush of sciatic nerve. Amongst all these no-invasive techniques of regeneration peripheral nerve, little known on the influence of the ultrasound in the regeneration of this tissue. Twenty six male Wistar rats weighing 289,61 g on average were used and divided into three groups: normal (N), injury (L) and injury+ultrasound (L+US). The application of the pulsed ultrasound (1 Mhz, 40 mW/\'CM POT.2\' and 8 minutes duration) was started one day after lesion and repeated for 4 week in alternate day. The functional analysis of the sciatic nerve (analysis of the march in track) was evaluated at weekly during all the experimental period. To verify the effectiveness of the ultrasound on nerve regeneration they had been analyzed sciatic functional index, morphology of the sciatic nerve and muscle morphology and morfometry of the muscles tibial anterior (TA) and sóleo (SOL). It was concluded that the treatment with the device of ultrasound of low intensity in regeneration peripheral nerve did not get resulted significant when compared the groups injured and injury+ultrasound, was only observed a maintenance of the cross-sectional area of the group injury+ultrasound of the muscle TA when compared with the normal group, taking the indications of that the ultrasound stimulated the nerve for such maintenance.
Larsson, Matilda. "Quantification and Visualization of Cardiovascular Function using Ultrasound." Doctoral thesis, KTH, Medicinsk teknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11762.
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Hassoun, Abdallah. "Ultrasound Transducers. Function and Quality Control in Hospitals." Thesis, KTH, Medicinsk teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103407.
Full textLi, Jian-Cheng. "Generation of simulated ultrasound images using a Gaussian smoothing function." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179261418.
Full textEnglund, Rickard. "Ultrasound Surface Extraction for Advanced Skin Rendering." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-98681.
Full textCheesman, M. G. "Right ventricular function in paced patients : a study using pulsed Doppler ultrasound." Thesis, University of Leicester, 1991. http://hdl.handle.net/2381/34299.
Full textBlaize, Kevin. "Cartographier le traitement de l'information visuelle cérébrale grâce aux ultrasons fonctionnels." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS114.
Full textIn the brain, the visual system includes the Lateral Geniculate Nucleus, the Superior Colliculus and the visual cortex. These structures have been studied since the 50’s and these studies have relied on functional MRI but also on the development of functional surface microscopic imaging techniques. To examine the spatiotemporal resolution of the ultrafast ultrasound imaging technique, we measured visual responses in in the cerebral structures on anesthetized rats in one imaging plan or with a 3D reconstruction. After having validated our technology on rodents, we have applied the technique to awake non-human primate visual cortex. We reconstructed the retinotopic maps of visual cortex, at the surface and in depth. In addition, we could resolve the ocular dominance columns within V1, which represent a major functional structuration in the primary visual cortex. This functional observation suggests the presence of ocular dominance beyond layer 4 in layers 3 and 5 of V1. In conclusion, this thesis work has demonstrated that the functional ultrafast ultrasound imaging can measure activity in the visual system for both rats and non-human primates, anesthetized and awake. This new imaging technique can provide functional measures with a high spatiotemporal resolution in the deep tissue. This illustration on the visual system highlights the potential of the technique to measure functional units not accessible to optical surface analysis and below the resolution of fMRI. Future studies will have to define if this technique can still provide a better resolution than fMRI in deeper structures than 1cm
Raso, Vanessa Vilela Monte. "Os efeitos do ultra-som terapêutico no tratamento das lesões por esmagamento do nervo ciático de ratos." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-29032006-162034/.
Full textAn experimental study of the influence of therapeutic ultrasound on the regeneration of the sciatic nerve submitted to controlled crush injury was carried out in rats. Twenty female Wistar rats weighing 250 g on average were used and distributed in two groups according to the procedure: 1) crush injury only, ten rats; 2) crush injury followed by ultrasound irradiation, ten rats. Under general anesthesia the sciatic nerve was exposed on the right thigh and crushed with a device especially devised and built for that purpose, with a 15 kg constant load for 10 minutes, affecting a 5 mm-long segment of the nerve proximal to its bifurcation. Pulsed ultrasound irradiation (1:5, 1 MHz frequency, 0.4 W/'CM POT.2' intensity, 2 minutes duration) was started the day after the operation and repeated for ten consecutive days. The results were evaluated by functional footprint analysis and determination of the sciatic functional index (DeMedinaceli's and Bain, Mackinnon and Hunter's methods) at weekly intervals, and by morphometry (nerve fiber density) of the resected sciatic nerve after killing the animals on the 21st postoperative day. Results were submitted to statistical evaluation and showed that, in the conditions of the study, ultrasound accelerated nerve regeneration, as demonstrated with significance on the 21st postoperative day
Tiran, Elodie. "Imagerie cérébrale et étude de la connectivité fonctionnelle par échographie Doppler ultrarapide chez le petit animal éveillé et en mouvement." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC174/document.
Full textMy work focuses on the application of fUS (functional ultrasound) imaging to preclinical brain imaging in small animals. The goal of my thesis was to turn this recent vascular brain imaging technique into a quantifying tool for cerebral state. The main objectives were to demonstrate the feasibility of fUS imaging in the non-anaesthetized small rodents and to move from rat model imaging to mouse model imaging –most used model for preclinical studies in neuroscience-, while developing the least invasive imaging protocols. First, I have developed a new ultrafast ultrasonic imaging sequence (Multiplane Wave imaging), improving the image signal-to-noise ratio by virtually increasing emitted signal amplitude, without reducing the ultrafast framerate. Then, I have demonstrated the possibility to use ultrafast Doppler ultrasound imaging to image both the mouse brain and the young rat brain, non-invasively and through the intact skull, without surgery or contrast agents injection. Next, I have developed an experimental setup, an ultrasound sequence and an experimental protocol to perform minimally invasive fUS imaging in awake and freely-moving mice. Finally, I have demonstrated the possibility to use fUS imaging to study the functional connectivity of the brain in a resting state in awake or sedated mice, still in a transcranial and minimally invasive way. fUS imaging and the combination of "mouse model" + "minimally invasive" + "awake animal" + "functional connectivity" represent a very promising tool for the neuroscientist community working on pathological animal models or new pharmacological molecules
Chambers, John Boyd. "Studies on the use of Doppler ultrasound in the assessment of prosthetic cardiac valve function." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390391.
Full textLovegrove, Jones Ruth Cerian. "Dynamic evaluation of female pelvic floor muscle function using 2D ultrasound and image processing methods." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/157609/.
Full textParamasivam, Gowrishankar. "Ultrasound assessment of fetal cardiac function and risk of adverse obstetric and neonatal outcomes in term fetuses." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/48187.
Full textWikström, Johannes. "Imaging of coronary artery function and morphology in living mice : applications in atherosclerosis research /." Göteborg : Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Göteborg University, 2007. http://hdl.handle.net/2077/3761.
Full textChouh, Hamza. "Simulations interactives de champ ultrasonore pour des configurations complexes de contrôle non destructif." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1220/document.
Full textIn order to fulfill increasing reliability and safety requirements, non destructive testing techniques are constantly evolving and so does their complexity. Consequently, simulation is an essential part of their design. We developed a tool for the simulation of the ultrasonic field radiated by any planar probes into non destructive testing configurations involving meshed geometries without prominent edges, isotropic and anisotropic, homogeneous and heterogeneous materials, and wave trajectories that can include reflections and transmissions. We approximate the ultrasonic wavefronts by using polynomial interpolators that are local to ultrasonic ray pencils. They are obtained using a surface research algorithm based on pencil tracing and successive subdivisions. Their interpolators enable the computation of the necessary quantities for the impulse response computation on each point of a sampling of the transducer surface that fulfills the Shannon criterion. By doing so, we can compute a global impulse response which, when convoluted with the excitation signal of the transducer, results in the ultrasonic field. The usage of task parallelism and of SIMD instructions on the most computationally expensive steps yields an important performance boost. Finally, we developed a tool for progressive visualization of field images. It benefits from an image reconstruction technique and schedules field computations in order to accelerate convergence towards the final image
Kasimoglu, Ismail Hakki. "Estimation of a Coronary Vessel Wall Deformation with High-Frequency Ultrasound Elastography." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19762.
Full textSun, Yurong. "Ultrasound characterization of structure and density of coral as a model for trabecular bone." Link to electronic version, 2000. http://www.wpi.edu/Pubs/ETD/Available/etd-0808100-001812/.
Full textKeywords: angular decorrelation function; impulse response; BUA; BMD; ultrasound; coral; trabecular bone; osteoporosis. Includes bibliographical references (p. 189-191).
Storaa, Camilla. "Investigations of strain calculated from ultrasound Doppler tissue velocities as tool for the assessment of left ventircular function." Licentiate thesis, KTH, Physics, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1404.
Full textAgnew, C. E. "Doppler Ultrasound Velocity Waveform and Retinal Image Assessment of Microvascular Function in Health and with Type 1 Diabetes." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527654.
Full textAl-Naser, Al Zekri Huda M. "Oligo/amenorrhoea : endocrine profiles, ovarian ultrasound, insulin resistan and anthropometric factors; relationships between insulin resistance and ovarian function." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360284.
Full textMeyers, Brett Albert. "Feasibility of Echocardiographic Particle Image Velocimetry for evaluation of cardiac left ventricular filling function." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/78159.
Full textMaster of Science