Thesis (M. Phil.)--University of Hong Kong, 2007. / Also available online.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Freehand; inertial tracking; Ultrasound. Includes bibliographical references (leaves 221-223).

Orientador: José Luiz Laus / Banca: Fabricio Vilella Mamede / Banca: Paola Castro Moraes / Resumo: A pesquisa foi desenvolvida visando-se a se avaliarem alterações nas dimensões de estruturas do bulbo de olho de cães da raça cocker spaniel inglês, machos e fêmeas, com e sem catarata, à ultrasonografia transcorneal nos modos A e B. Dezesseis pacientes (n = 16, 32 olhos, 10 machos, 6 fêmeas) com catarata e idade superior a 8 anos e um grupo controle sem catarata (n =7, 14 olhos, 2 manchos, 5 fêmeas) foram avaliados. Realizou-se ultrasonografia transcorneal nos modos A e B com transdutor de 10 MHz. Os dados referentes à ecobiometria, foram avaliados estatisticamente ao teste ANOVA de via única e os resultados expressos em média e desvio padrão (±DP). A incidência de catarata entre gênero foi avaliada estatisticamente ao teste de Fisher's. O comprimento axial do bulbo do olho dos pacientes com catarata e dos do grupo controle respectivamente, foi de 19.909 ± 1,103 mm; 19,958 ± 1,050mm. Para a câmara anterior, encontraram-se 3,041 ± 0,828 mm; 3,373 ± 1,040mm, respectivamente. Para o diâmetro lenticular foram de 6,817 ± 1,117 mm; 7,062 ± 0,477mm, respectivamente, e para o segmento posterior foram 10,056 ± 0,754mm; 9,523 ± 0,705mm. Não se encontraram diferenças significativas entre olhos com catarata e os controles, tampouco entre machos e fêmeas com e sem catarata. Tampouco foi encontrada diferença em quanto à incidência das cataratas entre ambos os sexos (P > 0.05). / Abstract: The present study was conceived to evaluate A- and B-mode ultrasonographic changes in the thickness of various structures of the eyeball in male and female English Cocker Spaniel dogs with and without cataracts. Sixteen dogs with cataracts (36 eyes, 10 males, 6 females), and seven normal dogs (14 eyes, 2 males, 5 females) older than eight years were selected. A- and B-mode ultrasonography was performed with a 10 MHz transducer. Echobiometry values were evaluated statistically by one way ANOVA. Incidence of cataract among gender was assessed by Fisher's excat test. Mean and standard deviations of various ocular structures for dogs with and without cataracts were, respectively, anterior chamber: 3.041 ± 0.828 mm, 3.373 ± 1.040 mm; lens: 6.817 ± 1.117 mm, 7.062 ± 0.477 mm; vitreous: 10.056 ± 0.754 mm, 9.523 ± 0.705 mm; and axial length: 19.909 ± 1.103 mm; 19.958 ± 1.050 mm. Ocular measurements between right and left eyes, males and females, as well as in eyes with and without cataract were not significantly different. Incidence between gender were not significantly (P > 0.05). / Mestre

Made available in DSpace on 2015-10-06T13:03:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-12-03. Added 1 bitstream(s) on 2015-10-06T13:18:56Z : No. of bitstreams: 1 000847380.pdf: 806327 bytes, checksum: f7d3032d99de2e92c79e98f58dfe233a (MD5) / Foi realizado estudo transversal, descritivo e observacional de 38 nervos ulnares de pacientes com hanseníase multibacilar, com idades entre 20 e 59 anos, com diagnóstico realizado na disciplina de dermatologia da Faculdade de Medicina de Botucatu (FMB-UNESP). Estes pacientes foram submetidos à palpação, exames de eletroneurografia e ultrassonografia dos nervos ulnares direito e esquerdo com o objetivo de estudar o comprometimento do nervo pela doença e comparar os resultados dos exames. Dos nervos estudados, nove (23,68%) não apresentaram nenhuma alteração nos resultados dos exames. Os que apresentaram alteração em um ou mais dos exames realizados, somaram 29 (76,32%). Os resultados foram comparados, e os que apresentaram alterações de normalidade em dois ou mais, foram denominados compatíveis. Houve compatibilidade de 20,68% entre clínica, eletroneurografia e ultrassonografia. Observou-se que esse fato ocorreu quando o exame ultrassonográfico mostrou valores próximos do dobro da normalidade. Não houve significância estatística entre os resultados apresentados; no entanto, deve-se considerar a correspondência entre os exames clínico, eletroneurográficos e ultrassonográficos / A cross-sectional, descriptive, observational study of 38 ulnar nerves of multibacillary patients, aged 20 to 59 years, with diagnosis made in Dermatology course of the Faculty of Medicine of Botucatu (FMB-UNESP). These patients underwent palpation, ultrasound exams and electroneurography ulnar nerve left and right in order to study the nerve disease involvement and compare the test results. The nerves studied, nine (23.68%) showed no change in the results of the examinations. Those who had alterations in one or more of the tests performed, totaled 29 (76.32%). The results were compared, and those with normal changes in two or more, were called compatible. There was 20.68% compatibility between clinical, electroneurography and ultrasound. It was observed that this actually occurred when the ultrasound examination showed values close to double the normal. There was no statistical significance between the results presented; however, one must consider the correlation between the clinical, electroneurographic and ultrasonography

M.Tech. / It is difficult to manage a pregnancy when fetal age, health status or potential pregnancy risks are not known. The aim of this study was to assess the impact of routine ultrasound screening as compared to selective use of ultrasound in the mid-trimester of pregnancy, on women using South African government health services. The three objectives investigated included assessment of the availability of reliable menstrual histories in the study population, the influence of ultrasound dating on obstetric management and the effect of ultrasound on pregnancy outcome due to the early detection of high risk pregnancies. A cluster randomised trial of 962 women was performed to test the hypothesis that midtrimester routine ultrasound screening in low risk pregnancies would result in improved antenatal care and perinatal outcome. Groups of eligible pregnant women were randomly selected to have either a routine scan followed by normal antenatal care or routine antenatal care which only allows for the selective use of ultrasound, in line with South African Antenatal Care Policy. Statistical analysis of the results confirmed that ultrasound dating is a more accurate predictor of the expected date of delivery when compared to other dating methods. Improved pregnancy dating resulted in a significant reduction in induction of labour for post-term pregnancy in the ultrasound screening group, suggesting a positive effect of ultrasound screening on obstetric management. No improvement was demonstrated in perinatal morbidity or mortality. The early detection of anomalous fetuses only led to one therapeutic abortion. The study did not possess the statistical power to demonstrate improved outcomes when multiple pregnancies were detected early in pregnancy. Currently there appears to be no urgent need to implement a routine antenatal screening programme in the Gauteng public health sector. In view of the fact that a third of the participants indicated that they were unsure of menstrual dates, and one third of the participants in the ultrasound screening group presented with an unreliable menstrual history, it is proposed that unsure dates be considered as a valid indication for the selective use of ultrasound in mid-trimester pregnancy.

Heart disease is the leading cause of death globally. Early diagnosis is the key to successful treatment. By providing noninvasive, non-ionizing, and real-time imaging, echocardiography plays a critical role in identifying heart disease. Compared to other imaging modalities, ultrasound has unparalleled temporal resolution. High frame-rate imaging has enabled the development of new metrics to characterize myocardial mechanics. Strain imaging measures the heart's deformation throughout the cardiac cycle, providing a quantitative assessment of cardiac health. The intention of this dissertation is to bring Myocardial Elastography (ME) closer to clinical realization. ME is a high frame-rate strain imaging technique for transthoracic and intracardiac echocardiography. This work consists of four Aims. There is a fundamental trade-off between spatial and temporal resolution in strain imaging. In Aim 1, the optimal transmit sequence that generates the most accurate and precise strain estimate was determined. Two common approaches to coherent compounding (full and partial aperture) were compared in simulation and in transthoracic imaging of healthy human subjects (n=5). The optimized subaperture compounding sequence (25-element subperture, 90° angular aperture, 10 virtual sources, 300 Hz frame rate) was compared to the optimized steered compounding sequence (60° angular aperture, 15° tilt, 10 virtual sources, 300 Hz frame rate) and was found to measure strain in healthy human subjects with equivalent precision. The optimal compounding configuration was then evaluated against two other high-frame rate transmit strategies, ECG-gated focused imaging, and wide-beam imaging, in simulation and in healthy subjects (n=7). Achieving the highest level of strain precision, ECG-gated focused imaging was determined to be the preferred imaging approach in patients capable of sustaining a breath hold, with compounding preferred in those unable to do so. Rapid diagnosis is essential to successful treatment of myocardial infarction. In Aim 2, ME's ability to track infarct formation and recovery, and localize infarct using regional strain measurments, was investigated in a large animal survival model (n=11). Infarcts were generated via ligation of the left anterior descending, imaging regularly for up to 28 days. A radial strain-based metric, percentage of healthy myocardium by strain (PHM_ε), was developed as a marker for healthy myocardial tissue. PHM_ε was strongly linearly correlated with actual infarct size as determined by gross pathology (R2 = 0.80). ME was capable of diagnosing individual myocardial segments as non-infarcted or infarcted with high sensitivity (82%), specificity (92%), and precision (85%) (ROC AUC = 0.90), and tracked infarct recovery from collateral reperfusion through time. Noninvasive strain imaging at rest can improve pre-test probability accuracy, and reduce unnecessary stress testing. In Aim 3, ME's potential to provide early diagnosis of coronary artery disease was investigated in an ongoing study. Patients undergoing myocardial perfusion imaging were recruited (n=126). Perfusion scores were used as the reference standard. Morphological transformations were integrated into the processing pipeline to reduce variability in the strain measurements. PHM_ε was reintroduced and used to differentiate between patients with and without coronary artery disease. ME was capable of distinguishing between normal patients and those with significant ischemia or infarct (subjects with perfusion defects at rest) with statistical significance (p < 0.05), although a greater sample size is needed to confirm the results. One of the most common treatments for arrhythmia, catheter ablation, can fail if the lesion line intended to terminate the abnormal rhythm is non-contiguous. In Aim 4, the gap resolution and clinical feasibility of Intracardiac Myocardial Elastography (IME) strain imaging, an ablation monitoring technique, was investigated. Lesion size estimation and gap resolution was evaluated in an open chest canine model (n=3), wherein lesion lines consisting of three lesions and two gaps were generated in each canine left ventricle via epicardial ablation. All gaps were resolvable. Average lesion and gap areas were measured with high agreement (33 ± 14 mm2 and 30 ± 15 mm2, respectively) when compared against gross pathology (34 ± 19 mm2 and 26 ± 11 mm2, respectively). Gaps as small as 11 mm2 (3.6 mm on epicardial surface) were identifiable. Patients undergoing ablation to treat typical cavotricuspid isthmus atrial flutter (n=5) were imaged throughout the procedure. In all patients, strain decreased in the cavotricuspid isthmus after ablation (mean paired difference of -17 ± 11 %, p < 0.05). Together, these Aims intend to translate a promising imaging method from research to clinical reality.

Diagnoses using images made with non-ionizing ultrasound are based on qualitive criteria and are not more accurate than those made with mammography. Information about tissue state is lost in the processing required to produce ultrasound images, and textural information may not be perceptible to a human observer. This study uses statistical pattern recognition to classify ultrasound A-scans, before any processing other than amplification occurs. A U. I. Octoson was used to collect data from normal, benign, and malignant, in vivo breast tissues. Features based on textural or frequency content of received sound were computed from digitized A-scans. Most textural features have been used previously in image processing, while frequency features assumed differences in frequency-dependent attenuation. Data were collected at the University of Arizona from 17 malignant masses, 8 benign masses, and 7 normal tissues. Univariate and multivariate statistical tests were used to find combinations of features which discriminated best between the classes of tissue. Equal a priori probabilities were used in a Bayesian classifier to classify malignant vs. nonmalignant. Specificity of 76% (13 of 17 malignant masses correct) was found with a sensitivity of 80% (12 of 15 masses correct). A linear combination of one frequency feature and three textural features was used. For malignant vs. benign, sensitivity of 88% (15 of 17 masses) and specificity of 75% (6 of 8 masses) were found. Features used were the same as for classification of malignant vs. nonmalignant, except for modification of one textural feature. The inability to visually detect and gather data from some palpable masses means that further study is needed to determine the effectiveness of applying the method to all breast masses. A set of A-scans from Thomas Jefferson Hospital in Philadelphia was gathered using similar procedures, and analysed with the following results: 18 of 21 (86%) malignant masses, and 45 of 66 (68%) nonmalignant masses were classified correctly, using a linear combination of one textural feature and five frequency features. Confidence limits on the results show that the majority of masses can be classified correctly with this procedure, but success rates are not high enough for breast cancer screening.

Thesis (Ph.D.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 173-179).

Recent studies have indicated that vascular stiffness is an important predictor of future cardiovascular disease. Hence, assessment of vascular stiffness would be of interest. Ultrasound is a good modality for assessment of vascular stiffness, due to its hight temporal resolution and non-invasive nature. Using ultrasound, various techniques have been proposedto estimate vascular stiffness, one of them being Pulse Wave Imaging. The ultimate goal of Pulse Wave Imaging is to provide a robust, qualitative and quantitative method to estimate and visualize clinically important parameters and phenomenonfor cardiovascular disease. The objective of this thesis limits itself to 1) expand Pulse Wave Imaging by going beyond just the diastolic stiffness, 2) utilize Pulse Wave Imaging in an atherosclerotic swine model to monitor plaque initiation and progression and 3) improve non-linear stiffness estimation at or near sites of reflections using Pulse Wave Imaging for clinical applications. In Aim 1, the question pursued was whether Pulse Wave Imaging can be utilized to monitor this non-linear behavior in-vivo. It was observed that in this mouse model, the compliance at diastolic pressure did not change significantly, whereas the compliance at end-systole did. Thus suggesting that Pulse Wave Imaging was able to monitor a change in non-linear stiffness, and that considering this, might be of importance. In Aim 2, the ability of Pulse Wave Imaging to monitor disease progression for atherosclerotic disease progression was assessed. Since human studies involve various compounding factors, animal models provide the opportunity to study the ability of methods in a more controlled manner. Swine is a good candidate due to its similarity with humans. To doso, first, the feasibility of Pulse Wave Imaging in swine needed to be assessed. While the cardiovascular system might be similar, various other factors, such as the location and depth of the carotid differs. It was revealed that PWI was feasible in swine and that we were able to generate atherosclerotic lesions within 9-months. Subsequently the ability of Pulse Wave Imaging and Vector Flow Imaging to monitor atherosclerotic progression leading to different type of lesions was assessed. The in-vivo findings were compared with histology and nanoidentation. The results indicated that Pulse Wave Imaging was shown to be able to separate to different disease progression pathways leading to different type of lesions. Finally in Aim 3, lessons learned from the animal models were attempted to be addressed by developing a more reflection robust approach for localized non-linear stiffness estimation for clinical application. First, improvements were proposed to a previously developed inverse problem approach that can resolve reflections within the field of view by including information from the flow velocity. To expand the approach to include non-linearity and reflections that occur outside the field of view, a physics-based neural network approach was considered. This might be of importance since most plaques are located at sites of significant reflections, such as the bifurcation. Chapter 6 revealed that artificial significant sources of reflections hindered its ability for sub-cm scale localized compliance measurements as indicated by an immediate increase in the number of detected segments after the ligation was induced. The approaches was validated using simulated data and feasibility was shown in in-vivo examples. With new progress, new issues tend to arise. Finally, the purpose of this sub-aim is to utilize the technique and investigate whether or not it can in fact better differentiate between different clinically relevant groups. The findings revealed no significant improvement concerning the mean compliance estimated, but appeared more robust against outliers when only the plaque segment was assessed. In conclusion, the results shown in this dissertation indicate that Pulse Wave Imaging is a promising approach to assess non-linear stiffness estimation for monitoring of vascular disease. Furthermore, an new methodology was proposed and feasibility was shown, which could further improve localized and non-linear stiffness estimation at or near sources of significant reflections, and which can be used as a starting point for further development.

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