Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 58-60). Also available in electronic version.

L’échographie clinique en médecine d’urgence (ECMU) devient une pratique intégrée à l’exercice de la spécialité. En France, son utilisation va se généraliser grâce à la formation de tous les nouveaux internes de médecine d’urgence. La pratique de l’ECMU demande l’existence de preuves scientifiques sur la pertinence diagnostique des techniques utilisées, la disponibilité d’un échographe adapté, la compétence de la pratiquer et l’objectivation de son impact clinique. Après avoir définit l’ECMU, ce texte décrit et analyse l’état d’avancement de ces quatre étapes. Les articles inclus dans ce texte s’intègrent dans chacune d’entre elles. Ils ont pour objectif de participer à trouver les solutions permettant le déploiement et l’évolution de l’ECMU. Enfin, des perspectives d’évolutions de l’ECMU sont proposées. / Emergency point-of-care ultrasound (EPOCUS) has become an integrated practice in emergency medicine. In France, systematic EPOCUS teaching for all emergency residents will lead to its widespread use. Integrating EPOCUS practice requires four steps: (1) the publication of accurate scientific data; (2) the availability of suitable ultrasound systems; (3) developing the necessary skills; and (4) highlighting its clinical impact. After defining EPOCUS, this manuscript describes and analyzes the progress of these four steps as the articles herein integrate into each. The aim is to find solutions for the deployment and evolution of EPOCUS. Finally, an outlook for future EPOCUS development is proposed.

Ultrasound screening has been used for decades as the main modality to examine fetal brain development and to diagnose possible anomalies. However, basic clinical ultrasound examination of the fetal head is limited to axial planes of the brain and linear measurements which may have restrained its potential and efficacy. The recent introduction of three-dimensional (3D) ultrasound provides the opportunity to navigate to different anatomical planes and to evaluate structures in 3D within the developing brain. Regardless of acquisition methods, interpreting 2D/3D ultrasound fetal brain images require considerable skill and time. In this thesis, a series of automatic image analysis algorithms are proposed that exploit the rich sonographic patterns captured by the scans and help to simplify clinical examination. The original contributions include: 1. An original skull detection method for 3D ultrasound images, which achieves mean accuracy of 2.2 ± 1.6 mm compared to the ground truth (GT). In addition, the algorithm is utilised for accurate automated measurement of essential biometry in standard examinations: biparietal diameter (mean accuracy: 2.1 ± 1.4 mm) and head circumference (mean accuracy: 4.5 ± 3.7 mm). 2. A plane detection algorithm. It automatically extracts mid-sagittal plane that provides visualization of midline structures, which are crucial to assess central nervous system malformations. The automated planes are in accordance with manual ones (within 3.0 ± 3.5°). 3. A general segmentation framework for delineating fetal brain structures in 2D images. The automatically generated predictions are found to be agreed with the manual delineations (mean dice-similarity coefficient: 0.79 ± 0.07). As a by-product, the algorithm generated automated biometry. The results might be further utilized for morphological evaluation in future research. 4. An efficient localization model that is able to pinpoint the 3D locations of five key brain structures that are examined in a routine clinical examination. The predictions correlate with the ground truth: the average centre deviation is 1.8 ± 1.4 mm, and the size difference between them is 1.9 ± 1.5 mm. The application of this model may greatly reduce the time required for routine examination in clinical practice. 5. A 3D affine registration pipeline. Leveraging the power of convolutional neural networks, the model takes raw 3D brain images as input and geometrically transforms fetal brains into a unified coordinate system (proposed as a Fetal Brain Talairach system). The integration of these algorithms into computer-assisted analysis tools may greatly reduce the time and effort to evaluate 3D fetal neurosonography for clinicians. Furthermore, they will assist understanding of fetal brain maturation by distilling 2D/3D information directly from the uterus.

Imaging the dome of the liver can be a very challenging area to image by Ultrasound. Due to its position inside the ribcage there can be difficulty with rib shadowing artifacts causing the sonographer to miss small lesions. The X6–1 Matrix transducer is one of the newest of its kind and claims to be the better multi-use transducer. Its larger aperture reduces rib artifacts and is composed of PureWave Crystal Technology. A phantom will serve as a great approach in this abdominal study to visually compare the lesions between MRI (gold standard) and the new X6–1 Matrix Ultrasound transducer. The X6–1 transducers did reveal minimal rib shadowing and the small lesions were identified.

Despite the prevalence of CNS disorders, treatment options for CNS disorders fall woefully behind treatment options for other systemic disorders. This is due to the presence of the blood brain barrier (BBB) acting as an obstacle, preventing foreign substances from entering the brain. A newly developed and innovative biomedical procedure attempts to bypass the BBB in the delivery of therapeutics by using focused ultrasound (FUS) to disrupt and temporarily open the BBB. The use of FUS-facilitated BBB opening is able to target specific tissue for noninvasive, localized BBB penetration. As the technique is experimental and in it's nascent stage of development, there are only a few studies that investigate its abilities in delivering treatments directly to the brain. The studies involve delivery of large, hydrophilic molecules that traditionally would not be able to bypass the BBB and enter the brain, and analysis of CNS concentrations of the molecules after FUS treatment, as well as the therapeutic successes. Results of FUS the studies are promising and the results demonstrate that the procedure is able to significantly increase drug concentrations in the brain, increase survival rates in animal models, decrease tumor growth, and decrease tumor margins and volume. The potential and power of FUS should be further explored as the future of CNS disorder treatments.

Ultrasound imaging plays an important role in biomedical diagnostics due its safety, noninvasive nature, and low cost. Conventional ultrasound systems typically form an image frame by scanning the region of interest line-by-line, using a focused beam during transmission and dynamic focusing during reception. Alternatively, the region of interest can be insonified at once using a plane wave, which allows for ultrafast data acquisition rates but reduces the resulting image quality. The latter can be improved by means of coherent plane-wave compounding (CPWC), whereby multiple plane waves are emitted at different angles to obtain multiple image datasets that are subsequently combined to enhance the final compounded image. We present two novel Fourier-domain techniques for CPWC image reconstruction from raw linear-array sensor data. In particular, we show how to modify two classic algorithms used for geophysical data processing, namely Stolt's and slant-stack depth migration under zero-offset constant-velocity assumptions, so that their new versions become applicable to plane-wave ultrasound data processing. To demonstrate the merits and limitations of our approach, we provide qualitative and quantitative comparisons with other Fourier-domain methods reported in the ultrasound literature. Our evaluation results are based on the image resolution, contrast, and similarity metrics obtained for several public-domain experimental benchmark datasets. We also describe another novel Fourier-domain method for CPWC image reconstruction that can be used in situations where the speed of sound varies with depth in a layered propagation medium. Our technique builds on Gazdag's phase-shift migration algorithm that has been modified to handle plane-wave ultrasound data processing. Our simulation results show that the proposed method is capable of accurately imaging point targets in a three-layer medium, mimicking tissue-bone-tissue ultrasound propagation. / Graduate

It is believed, that due to the large surface areas provided by the nano scale materials, various composite properties could be enhanced when such particles are incorporated into a polymer matrix. There is also a trend of utilizing natural resources or reusing and recycling materials that are already available for the fabrication of the new composite materials. Cellulose is the most abundant natural polymer on the planet, and therefore it is not surprising to be of interest for composite fabrication. Basic structures of cellulose, comprised of long polysaccharide chains, are the building blocks of cellulose nano fibers. Nano fibers are further bound into micro fibrils and macro fibers. Theoretically pure cellulose nano fibers have tremendous strengths, and therefore are some of the most sought after nano particles. The fiber extraction however is a complex task. The ultrasound, which creates pressure variation in the medium, was employed to extract nano-size cellulose particles from microcrystalline cellulose (MCC). The length and the intensity of the cavitations were evaluated. Electron microscopy studies revealed that cellulose nanoparticles were successfully obtained from the MCC after ultrasound treatment of just 30 minutes. Structure of the fractionated cellulose was also analyzed with the help of X-ray diffraction, and its thermal properties were evaluated with the help of differential scanning calorimetry (DSC). Ultrasound treatment performed on the wheat straw, kenaf, and miscanthus particles altered fiber structure as a result of the cavitation. The micro fibers were generated from these materials after they were subjected to NaOH treatment followed by the ultrasound processing. The potential of larger than nano-sized natural fibers to be used for composite fabrication was also explored. The agricultural byproducts, such as wheat or rice straw, as well as other fast growing crops as miscanthus or kenaf, are comprised of three basic polymers. Just like in wood the polymers are: cellulose, hemicelluloses, and lignin. When subjected to elevated pressures and temperatures, we are able to get access to some of these natural polymers and use them as a matrix material for composite fabrication. Therefore, fabrication of composite materials without addition of synthetic polymers is possible. Thermal and mechanical properties of such composites are evaluated with the help of electron microscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and flexural strength measurements. The chemical changes in the composites are also probed with the help of Fourier transform infrared (FTIR) analysis. Various additives introduced into composite materials provide different properties. The addition of small amounts of synthetic polymers further enhances the properties of natural fiber composites and do not require high fabrication pressures. Calcium sulfite crystals, which are one of the coal combustion products, were combined with the natural fibers and recycled HDPE polymer to form wood substitute composites. The introduction of these additives resulted in composites with the properties similar to those of the natural wood. Coal combustion products, often used in composite material fabrication, contain mercury which may be rereleased during composite fabrication. Mercury behavior under composite fabrication conditions, such as elevated pressures and temperatures were evaluated. Sulfite rich scrubber material, generated during the flue gas desulphurization process was the main target of the study. It was observed that the release of the mercury is highly dependent on the composite fabrication pressure as well as the temperature.

In this research, through-transmission ultrasonic (TTU) Acoustography was applied to measure and quantify porosity levels in carbon fiber reinforced polymer (CFRP) composite laminates. This study employed several CFRP specimens with wide ranges of porosity prepared by altering the curing pressure during the manufacturing process. The Acoustography method, operating at 5 MHz, was able to show contrast in ultrasonic images obtained for composite laminates with varied porosity levels. Porosity levels in composite laminates were quantified using destructive methods: acid digestion and microscopy. Also, strength analysis tests were conducted to investigate the effect porosity has on the laminate’s structural integrity. From the results obtained, it was demonstrated that the mechanical properties, interlaminar shear strength (ILSS), and flexural strength of CFRP decreased with the increasing void content. In addition, Acoustography absorption coefficient measurements were related to varied porosity levels in the composite laminates. As the porosity content increased within the laminates, the acoustic absorption coefficient increased. These findings are significant because Acoustography is being developed as a faster alternative to traditional ultrasonic inspection of composites and porosity is an important anomaly to quantify utilizing NDE methods.

Made available in DSpace on 2014-06-11T19:26:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-18Bitstream added on 2014-06-13T20:34:48Z : No. of bitstreams: 1 brandao_gms_me_botfm.pdf: 1478164 bytes, checksum: 2a2a85c3df30f48b27dadc4c51f20e91 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Universidade Estadual Paulista (UNESP) / A trombose venosa profunda (TVP) dos membros inferiores é doença grave, potencialmente fatal e pode levar à síndrome pós-trombótica (SPT). A SPT é doença crônica, com consideráveis conseqüências socioeconômicas para os pacientes serviços de saúde. Sua fisiopatologia relaciona-se com o surgimento de hipertensão venosa, que ocorre devido à incompetência valvular e a obstrução da veia pelo trombo residual. Assim, é importante conhecer o processo de recanalização das veias trombosadas para melhor compreensão das seqüelas da TVP. Avaliar e quantificar o processo inicial de recanalização das veias dos membros inferiores após um episódio de TVP aguda pelo mapeamento dúplex em cores (MDC). Estudou-se pelo MDC 12 pacientes na fase aguda (até 10 dias), no 1°, 3º e 6º mês após o episódio agudo de TVP. Os pacientes foram mantidos com terapia anticoagulante adequada por 6 meses e orientados a usar meias de compressão elástica. Para avaliar e quantificar a recanalização foram utilizados o escore trombótico (ET) e a variação percentual do diâmetro venoso na máxima compressibilidade em relação a sua ausência (Δ%Øvmax/Øvsem). O ET foi verificado em 18 segmentos venosos (veias ilíaca externa; femoral comum; femoral profunda; femoral ao nível da junção e a 10 cm da prega inguinal; poplítea supra patelar e cavo; fibulares; tibiais posteriores; gastrocnêmias; soleares; veia safena magna ao nível da crossa, terço proximal, médio e distal; veia safena parva ao nível da crossa, terço proximal e médio). Segmentos venosos patentes tiveram ET de zero. A TVP foi considerada parcialmente oclusiva quando o segmento venoso foi não compressível com um sinal Doppler presente (ET = 1). Considerou-se a TVP totalmente oclusiva quando o segmento venoso foi não compressível e o sinal Doppler não foi encontrado (ET = 2). Para cada membro foi calculado o ET total... / The deep vein thrombosis (DVT) of the lower limbs is a serious, potentially fatal disease and it can lead to the post-thrombotic syndrome (PTS). The PTS is a chronic disease, with considerable social and economical consequences for the patients and health services. His physiopathology is connected with the appearance of vein high blood pressure that takes place due to the valval incompetence and the obstruction of the vein for the residual thrombus. So, it is important to know the process of recanalization of the thrombosed veins for better understanding of the sequels of the DVT. The objective of this study was to evaluate and quantify the early recanalization of the vein of the lower limbs after acute DVT by duplex ultrasound scanning (DUS). Twelve elegible patients were examined by DUS at acute phase (less than 10 days), 1°, 3º and 6º months after the first episode of DVT. All patients were treated initially with unfractionated heparin or low-molecular-weightheparin followed by oral anticoagulation for 6 months and strongly encouraged to use compression stockings. To evaluate and quantify the recanalization of the veins were used the thrombus escore (TS) and the percentage variation of the vein diameter during the maximal compressibility regarding his absence (PVVDMA). The thrombus score (TS) assigned to 18 vein segments: external iliac vein; common femoral vein; deep femoral vein; confluence of femoral and deep femoral vein; femoral vein 10 cm at the inguinal ligament; popliteal vein suprapatellar; popliteal vein fossa; fibular veins; posterior tibial veins; gastrocnemius veins; soleal veins; sapheno-femoral junction; grate saphenous... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:23:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-24Bitstream added on 2014-06-13T20:48:18Z : No. of bitstreams: 1 muller_tr_me_botfmvz.pdf: 611957 bytes, checksum: 80f25eafd27a820a15d30aa300288f05 (MD5) / Fundação para o Desenvolvimento da UNESP (FUNDUNESP) / A glândula tireóide foi avaliada ultrassonograficamente em cães hígidos de médio porte em diferentes faixas etárias. O objetivo do estudo foi de verificar padrões de imagem nestes grupos, assim como identificar possíveis alterações de imagem decorrentes do aumento da idade. 30 cães, 10 jovens, 10 adultos e 10 idosos, sem sinais clínicos ou história de doença tireoidiana, com exames de hemograma e testes de função tireóidea dentro dos valores normais de referência foram avaliados. Cada lobo tireoidiano foi examinado ultrassonograficamente quanto ao formato, tamanho, ecogenicidade e ecotextura. As análises de ecogenicidade e ecotextura foram realizadas por histograma. O volume tireoidiano foi estimado pela equação para elipsóides (comprimento x altura x largura)π/6. Os resultados obtidos indicam que, em cães jovens, o volume tireoidiano apresenta uma tendência de ser maior do que em cães adultos (p= 0, 068). No plano longitudinal da tireóide foi constatada uma variação significativa maior da altura do lobo tireoidiano nos cães jovens quando comparada aos outros cães. A ecotextura e ecogenicidade não tiverem diferença significativa entre os grupos, contudo a ecogenicidade foi maior em cães idosos. Os resultados sugerem que a imagem ultrassonográfica da tireóide sofre influência da idade em cães de médio porte / The thyroid gland was assessed by ultrasound in healthy medium size dogs in different age groups. The objective was to verify patterns of image in these groups, as well as identify possible changes in image resulting from aging. Thirty dogs - 10 young, 10 adult and 10 elderly - without clinical signs or history of thyroid disease, with CBC and thyroid function tests within the reference values were evaluated. Each thyroid lobe was examined by ultrasound for shape, size, echogenicity and echotexture. The analysis of echogenicity and echotexture was made by histogram. Thyroid volume was estimated by the equation for ellipsoid (length x width x height) π / 6. The results indicate that the thyroid volume of young dogs has a tendency to be higher than in adult dogs (p = 0. 068) and older dogs (p= 0. 120). The height of thyroid lobe in the longitudinal plane was significantly higher in young dogs compared with the other dogs. The echotexture and echogenicity had no significant difference between groups, but the echogenicity was greater in older dogs. The results indicate that ultrasound imaging of the thyroid is influenced by age in dogs of medium size