abstract: Transcranial focused ultrasound (tFUS) is a unique neurostimulation modality with potential to develop into a highly sophisticated and effective tool. Unlike any other noninvasive neurostimulation technique, tFUS has a high spatial resolution (on the order of millimeters) and can penetrate across the skull, deep into the brain. Sub-thermal tFUS has been shown to induce changes in EEG and fMRI, as well as perception and mood. This study investigates the possibility of using tFUS to modulate brain networks involved in attention and cognitive control.Three different brain areas linked to saliency, cognitive control, and emotion within the cingulo-opercular network were stimulated with tFUS while subjects performed behavioral paradigms. The first study targeted the dorsal anterior cingulate cortex (dACC), which is associated with performance on cognitive attention tasks, conflict, error, and, emotion. Subjects performed a variant of the Erikson Flanker task in which emotional faces (fear, neutral or scrambled) were displayed in the background as distractors. tFUS significantly reduced the reaction time (RT) delay induced by faces; there were significant differences between tFUS and Sham groups in event related potentials (ERP), event related spectral perturbation (ERSP), conflict and error processing, and heart rate variability (HRV). The second study used the same behavioral paradigm, but targeted tFUS to the right anterior insula/frontal operculum (aIns/fO). The aIns/fO is implicated in saliency, cognitive control, interoceptive awareness, autonomic function, and emotion. tFUS was found to significantly alter ERP, ERSP, conflict and error processing, and HRV responses. The third study targeted tFUS to the right inferior frontal gyrus (rIFG), employing the Stop Signal task to study inhibition. tFUS affected ERPs and improved stopping speed. Using network modeling, causal evidence is presented for rIFG influence on subcortical nodes in stopping. This work provides preliminarily evidence that tFUS can be used to modulate broader network function through a single node, affecting neurophysiological processing, physiologic responses, and behavioral performance. Additionally it can be used as a tool to elucidate network function. These studies suggest tFUS has the potential to affect cognitive function as a clinical tool, and perhaps even enhance wellbeing and expand conscious awareness. / Dissertation/Thesis / Doctoral Dissertation Bioengineering 2020

Work describe principles and problems of the realization ultrasonic anemometer. It's described methods of computation speed wind and its correction. In favor of realization are used ultrasonic transducers and microcontroller ARM Cortex-M3. The work treats PWM signal generating, its analog filtration, amplification and transmitting. On receiving part there are low voltage amplifier and comparator. Developing code is described by flowcharts.

As a main in this project is the shape. The feature component for completely creation look was the conception of the base part of the machine with buit-in computer unit. I was get along from the base conception to the design partial fragments of the machine and associate complex look of ultrasound. The function of the machine is relatively difficult and analysis of it is complicated in time. That is why I am introducing only evolution of design and ergonomy. The aspire was to approach medical diagnostic machines to patients and raise the positive thinking to them. The colour alternation is choose with the respect to psyche of examine human at the same time.

This master's thesis is concerned with the basis of ultra-acoustics and it explains the application of Doppler effect in medicine as a diagnostic method used for measuring blood flow velocity in blood vessels. The thesis also presents Doppler systems used for diagnostic purposes. It describes the principles of these systems, shows accompanying flowcharts and explains the function of these systems. There is also included the system design of the whole ultrasonic blood flow velocity meter. The system has been designed for the specified parameters with continuous 4 MHz operating frequency, generated intensity of ultrasound 100 mW/cm^2 and diameter D-shaped transmitting transducer 8 mm. In the design of personal solution there are described all the function blocks of the ultrasonic meter. There is also described the choice of appropriate components and designed all the required supply voltages. All the function blocks of the system are experimentally verified. The system has been designed with acoustic intercept and the resultant velocity curves are displayed on software oscilloscope on PC.

L’élastographie est une modalité d'imagerie médicale émergente qui permet de mesurer les propriétés mécaniques des tissus moux humains. Ces mesures peuvent servir de biomarqueurs pour l'amélioration de la prise en charge des maladies, du diagnostic précoce et de l'évaluation de la sévérité, au suivi de la réponse au traitement. Parmi les différentes approches de l’élastographie, l'élastographie par Résonance Magnétique (ERM) et l’élastographie ultrasonore par ondes de cisaillement (Supersonic Shear Imaging (SSI)) suscitent des intérêts particuliers. Ces deux modalités ont été largement étudiées pour des applications cliniques multiples. Toutefois, chaque modalité repose sur des conditions d'acquisition et de reconstruction différentes et caractérisées par leur propres limites qui peuvent induire des biais de mesure intra-et inter-modalité et donc entraver l'interchangeabilité des deux modalités pour des applications cliniques. Dans un premier temps, ma thèse a porté sur l'identification des biais de mesure entre ERM et SSI. Grâce à une comparaison méthodologique approfondie des deux modalités, nous avons identifié les différentes caractéristiques de fréquence des ondes de cisaillement générées par les deux modalités et les contraintes spécifiques de reconstruction, en particulier en ERM, comme les principales sources de biais de mesure entre les deux modalités. Dans un deuxième temps, une étude de simulation a étéeffectuée afin de caractériser l'influence des conditions d'acquisition et de reconstruction sur l'exactitude et la précision des mesures d’ERM. Nous avons établi des abaci in silico pour identifier le nombre de voxels par longueur d'onde idéal (rapport λ/a) pour obtenir des mesures ERM exactes et précises. En outre, nous avons montré que le rééchantillonnage pouvait s’avérer efficace afin de répondre aux critères de λ/a favorable lorsque le nombre de voxels par longueur d'onde initial était mal défini. Les résultats finaux, qui sont généralement calculés à partir des trois directions d'encodage, peuvent être améliorés grâce à des stratégies de pondération appropriées qui reposent sur le champ rotationnel du déplacement de l'onde de cisaillement. Pour la modalité SSI, nous avons utilisé le paramètre de qualité fourni par le fabricant afin d’éliminer raisonnablement des résultats peu fiables et améliorer encore la qualité des mesures. Ensuite nous avons intégré les stratégies d'optimisation proposées dans chaque modalité pour effectuer des études de comparaison expérimentales impartiales entre ces deux modalités. Des études in vitro ont été effectuées sur des fantômes commerciaux calibrés et aussi des fantômes à la base de l'alcool polyvinylique. Des résultats expérimentaux confirment bien ceux de la simulation. Des mesures SSI et ERM sont en bon accord quand des biais reliés à la théorie, l'expérimentation et la reconstruction sont minimisés. Des études in vivo ont été ensuite effectuées sur le foie de deux volontaires sains. On a constaté que lorsque le foie est quasi-élastique, des mesures SSI et ERM avec la qualité optimisée concordent bien les uns et les autres, ils sont donc interchangeables. Dans le cas du tissu hépatique viscoélastique, des mesures SSI et ERM dépendent de la fréquence. Dans ce contexte, des mesures ERM et SSI pour la même fréquence spécifique sont nécessaires pour réaliser une comparaison impartiale entre des deux modalités. / Elastography is an emerging medical imaging modality which permits to measure the mechanical properties of human soft tissue. The measured mechanical properties can serve as potential biomarkers for improving the management of diseases, from early diagnosis, to severity evaluation and therapy response monitoring. Among different approaches, Magnetic Resonance Elastography (MRE) and Supersonic Shear Imaging (SSI) have shown particular interests. The two modalities have been widely investigated for multiple clinical applications. However, each modality is challenged by specific acquisition and reconstruction conditions which may induce intra- and inter-modality measurement biases and hence impede the interchangeability of the two modalities. The first part of my thesis focused on identifying the measurement biases between MRE and SSI. Through a thorough methodological comparison study, we recognized different frequency characteristics of generated shear waves for the two modalities and modality specific reconstruction validity issues as the main sources for the measurement biases between the two modalities. Then through a dedicated simulation study, we established an in silico abaci to identify the favorable range of number of voxels per wavelength which leads to accurate and precise MRE. Moreover, resampling was proven effective to regulate poorly defined number of voxels per wavelength to the favorable range. The overall outcome, which is usually computed from the three acquired motionencoded directions, may further be improved by appropriate weighting strategies that are based on curl of shear displacement field. For SSI, we referred to the quality parameter provided by the manufacturer to reasonably eliminate unreliable results so as to further improve the measurement quality. After establishing the potential measurement biases between MRE and SSI, we incorporated the proposed quality optimization strategies into both modalities in order to perform unbiased experimental comparison studies between the two modalities. First, in vitro studies were carried out on commercial calibrated phantoms as well as home-made polyvinyl alcohol phantoms. Experimental results corroborate well the simulation findings. MRE and SSI measurements agree well witheach other when theory, experiment, and reconstruction biases are minimized. In vivo studies were then performed on the livers of two healthy volunteers. We found that when the liver is quasi-elastic, the quality-guided MRE and SSI measurements agree well with each other and hence are interchangeable. In case of viscoelastic liver tissue, both MRE and SSI measurements are frequency dependent. Thus frequency-specific measurements are essential for cross-validating the measurements of these two modalities.

Ultrafast plane-wave ultrasound imaging offers very high frame rates (exceeding thousands of frames per second) but entails large volumes of backscattered data collected by a sensor array over multiple plane-wave emissions at different angles. We propose a simple method for reducing the total amount of sampled data. First, we acquire the zero-angle data in full, and then we perform deterministic subsampling of the remaining nonzero-angle data. Our subsampling patterns are angle-specific and derived based on the zero-angle data using a Fourier-domain migration technique. We use two experimental datasets to evaluate the benefits and drawbacks of our proposed method in terms of spatial resolution and contrast-to-noise ratio, observed in the resulting B-mode images. / Graduate

<p>The diminutive size of microrobots makes them advantageous for minimally invasive operations and precise, localized treatment. One such application is aiding in localized drug delivery for colorectal cancer as microrobots could offer reduced patient trauma, lower risk of side effects, and higher drug retention rates. In this study, we evaluate the abilities of a magnetic microrobot in a variety of conditions using a high frequency ultrasound system. Under the influence of an external rotating magnetic field, the microrobot tumbles end-over-end to propel itself forward. Cytotoxicity tests demonstrated the constituent materials of polydimethylsiloxane (PDMS) and SU-8 were nontoxic to murine fibroblasts. Then, we quantified robot locomotion in an <i>ex vivo</i> porcine colon, testing the materials, the tumbling orientation, and three magnet rotation frequencies. Significant differences were found between materials and tumbling orientation, revealing that SU-8 lengthwise microrobots were the fastest with an average velocity of 2.12±0.25mm/s at a frequency of 1Hz. With this finding, the next tests were completed at 1Hz frequency with SU-8 lengthwise microrobots. We used <i>in vitro</i> agarose gels to maneuver the robot through a variety of trajectories, tested the microrobots <i>in situ</i> and <i>in vivo</i> murine colons as well. Average velocities were calculated for all tests with the <i>in vivo</i> murine colon tests finding an average velocity of 2.07±0.05mm/s. Finally, the microrobots were coated with a fluorescein payload and were shown to release a payload over a one-hour time period. These findings suggest microrobots are promising for targeted drug delivery and other <i>in vivo</i> biomedical applications.</p>

This descriptive retrospective cohort study utilized a large workers comp insurer database. All MRI's performed on peripheral joints during calendar year 2017 that were (a) 2 weeks after the initial clinic visit, or (b) greater than 6 weeks after injury, but (c) not more than 3 months after the date of injury were evaluated in this study. Individual diagnoses rendered on MRI reports for these cases were categorized as to whether ultrasound alone or ultrasound + xray could adequately provide the same diagnoses. Results showed that, ultrasound + xray would be able to provide all of the same diagnoses compared to MRI in 54% of cases vs 33% of cases using ultrasound alone, highlighting the utility of using ultrasound and xray together. The proportion of cases where ultrasound + xray could reasonably be substituted for MRI increases to 70% overall when less severe diagnoses, considered not likely to change management, were excluded from analysis. If point of care ultrasound was performed for all 1482 cases with subsequent MRIs pursued in only 30% of cases, a cost savings between $456,186 and $331,698 would be realized, translating to $308 to $224 per patient. Additionally, if ultrasound + xray was performed at the point of care during the first clinic visit for an injury, the definitive diagnoses could be reached on average 33.3 days earlier. In total, these results suggest a significant proportion of musculoskeletal workers comp injuries could be accurately and completely evaluated at the point of care using ultrasound and xray together. This could yield greater provider and patient confidence in the diagnosis and treatment plan as well as more expeditious accurate diagnoses leading to reductions in both direct and indirect costs.

Measuring the concentration of particles in water is important in many areas. Industries might measure it to run more efficiently while scientists might measure it to study the pollution of a body of water. Regardless of the area, the standard for taking a measurement is done by filtering out the particles by hand. This is a very slow and expensive method, so other alternative methods have been developed. However, all the alternative methods can only estimate the concentration. Therefore, Deepoid AB aims to investigate if ultrasound can be used to measure the concentration of particles in water.\parThis thesis shows that a direct ultrasound signal can be used to measure changes in the concentration of particles in water. It also shows how this method is much faster than measuring the concentration of particles in water by hand.

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