Successful treatment of myocardial infarction requires anearly and accurate diagnosis. Recent studies have shown thatacute myocardial scintigraphy has a high predictive value forprognosis of myocardial events. Three dimensional (3D)perfusion data obtained with SPECT are however very rare in theemergency department (ED). We have developed a mobile tomographic system for myocardialscintigraphy, which can be used in the ED. The objectives ofthe studies presented were:     To develop software and hardware for a mobile tomographicgamma camera system: the Cardiotom     To demonstrate that a mobile tomographic system can beused in a clinical situation     To evaluate the limitations of Ectomography when usingfiltered back projection for reconstruction     To develop a method of reconstruction that compensatesfor the incomplete data acquisition associated with theacquisition geometry of Ectomography Three prototypes of a mobile tomographic gamma camera systemhave been designed and built at the Division of MedicalEngineering, which all have been used in a clinical setting.The systems are based on Ectomography, a limited view anglemethod, also developed by us. Instead of rotating the entiregamma camera detector around the patient as in SPECT, a slanthole collimator is rotated in front of a stationary detector.Since short imaging times are important in the ED and the heartonly occupies a small area of the detector, system sensitivityhas been increased by dividing the collimator into segmentswith different projection directions. In myocardial imaging, 4segments are used and within 10 minutes from the start ofacquisition, reconstructed short axis view sections areavailable for interpretation. Using the Cardiotom in an experimental animal study, weverified that the system could be used to quantify myocardialarea at risk and final infarct size. This conclusion was madefrom a comparison of images obtained from the Cardiotom andpathological staining of the myocardium, analysedpost-mortem. Inherent limitations of Ectomography were evaluated withboth phantom studies and computer simulated data, reconstructedusing filtered back-projection Results show that moderatedeviation from optimal position of the detector with respect tothe myocardium will have little or no influence on thediagnostic information when assessed from short axis sectionimages and polar tomograms. However, long axis section imagesappear elongated when reconstructed using filteredback-projection. We have shown that this elongation distortion can besuppressed using iterative reconstructions techniques, and wehave implemented such an algorithm, called three-dimensionalTotal Variation Expectation Maximisation (3DTV-EM). Resultswere that elongation distortion was reduced and depthresolution improved. The reconstruction technique was alsoevaluated for SPECT reconstruction and was found to decreasethe noise in reconstructed images, when compared to thetwo-dimensional TV-EM algorithm. Noise pattern were also foundto be more uniform for the 3DTV-EM algorithm compared totwo-dimensional TV-EM. In conclusion, we have shown that the Cardiotom may beuseful in a clinical acute setting, providing valuablediagnostic information. Rapid positioning is possible, sincemoderate deviation from optimal positioning will cause few orno artefacts. Image quality can be improved if iterativetechniques are used for image reconstruction instead offiltered back-projection. <b>Keywords</b>: acute studies, myocardial infarction,scintigraphy, mobile gamma camera, tomography.

No description available.

No description available.

<p>Successful treatment of myocardial infarction requires anearly and accurate diagnosis. Recent studies have shown thatacute myocardial scintigraphy has a high predictive value forprognosis of myocardial events. Three dimensional (3D)perfusion data obtained with SPECT are however very rare in theemergency department (ED).</p><p>We have developed a mobile tomographic system for myocardialscintigraphy, which can be used in the ED. The objectives ofthe studies presented were:</p><p>    To develop software and hardware for a mobile tomographicgamma camera system: the Cardiotom</p><p>    To demonstrate that a mobile tomographic system can beused in a clinical situation</p><p>    To evaluate the limitations of Ectomography when usingfiltered back projection for reconstruction</p><p>    To develop a method of reconstruction that compensatesfor the incomplete data acquisition associated with theacquisition geometry of Ectomography</p><p>Three prototypes of a mobile tomographic gamma camera systemhave been designed and built at the Division of MedicalEngineering, which all have been used in a clinical setting.The systems are based on Ectomography, a limited view anglemethod, also developed by us. Instead of rotating the entiregamma camera detector around the patient as in SPECT, a slanthole collimator is rotated in front of a stationary detector.Since short imaging times are important in the ED and the heartonly occupies a small area of the detector, system sensitivityhas been increased by dividing the collimator into segmentswith different projection directions. In myocardial imaging, 4segments are used and within 10 minutes from the start ofacquisition, reconstructed short axis view sections areavailable for interpretation.</p><p>Using the Cardiotom in an experimental animal study, weverified that the system could be used to quantify myocardialarea at risk and final infarct size. This conclusion was madefrom a comparison of images obtained from the Cardiotom andpathological staining of the myocardium, analysedpost-mortem.</p><p>Inherent limitations of Ectomography were evaluated withboth phantom studies and computer simulated data, reconstructedusing filtered back-projection Results show that moderatedeviation from optimal position of the detector with respect tothe myocardium will have little or no influence on thediagnostic information when assessed from short axis sectionimages and polar tomograms. However, long axis section imagesappear elongated when reconstructed using filteredback-projection.</p><p>We have shown that this elongation distortion can besuppressed using iterative reconstructions techniques, and wehave implemented such an algorithm, called three-dimensionalTotal Variation Expectation Maximisation (3DTV-EM). Resultswere that elongation distortion was reduced and depthresolution improved. The reconstruction technique was alsoevaluated for SPECT reconstruction and was found to decreasethe noise in reconstructed images, when compared to thetwo-dimensional TV-EM algorithm. Noise pattern were also foundto be more uniform for the 3DTV-EM algorithm compared totwo-dimensional TV-EM.</p><p>In conclusion, we have shown that the Cardiotom may beuseful in a clinical acute setting, providing valuablediagnostic information. Rapid positioning is possible, sincemoderate deviation from optimal positioning will cause few orno artefacts. Image quality can be improved if iterativetechniques are used for image reconstruction instead offiltered back-projection.</p><p><b>Keywords</b>: acute studies, myocardial infarction,scintigraphy, mobile gamma camera, tomography.</p>

The human stomach is a complex organ with sophisticated function. – The control of delivery of nutrients to the small intestine is tightly regulated, and the patterns and determinants of the associated processes are numerous, complex and interrelated. The presence of nutrients in the small intestine stimulates the release of a number of gastrointestinal hormones, including glucagon-like peptide-1 (GLP-1). Exogenous GLP-1 reduces fasting and postprandial glucose concentrations, and this is thought to be via a slowing of gastric emptying (GE). The effects of endogenous GLP-1 on GE and glycaemia were evaluated using exendin(9-39), a GLP-1 antagonist, in healthy subjects, in a randomised, placebo-controlled study, in Chapter 5. Exendin(9-39) increased postprandial glycaemia through an acceleration of GE; these findings support the putative role of GLP-1 as an enterogastrone. The capacity to measure GE has greatly increased the understanding of normal and disordered gastric physiology. 30 – 50 % of patients with longstanding diabetes have delayed GE. Scintigraphy remains the ‘gold standard’ in the measurement of GE, however, it is associated with a radiation burden. Recently, three-dimensional (3D) ultrasonography was validated against scintigraphy in healthy subjects. In Chapter 6, GE was measured concurrently by 3D ultrasonography and scintigraphy in patients with diabetic gastroparesis, and good correlation and agreement was found between both techniques. Glycaemic control represents one of the main pathogenetic factors of diabetic gastroparesis. Hyperglycaemia slows, while hypoglycaemia accelerates, GE in healthy subjects and patients with uncomplicated type 1 diabetes. Chapter 7 reports a study investigating the effects of insulin-induced hypoglycaemia vs. euglycaemia on GE in longstanding type 1 diabetes. Hypoglycaemia accelerated GE of a mixed solid/liquid meal; the magnitude of this acceleration was greater when GE during euglycaemia was slower. In contrast to glucose, the effects of intravenous (iv) fructose (used widely in the diabetic diet) on GE are less well understood. The comparative effects of iv fructose, glucose and saline on GE and antropyloroduodenal motility in healthy males are reported in Chapter 8. Compared with saline, fructose infusion was associated with a slowing of GE and suppression of antral waves, the magnitude of which was comparable to glucose. Treatment for the management of gastroparesis is currently suboptimal and there is a need for novel prokinetic agents. Itopride has demonstrated prokinetic activity in dogs. The effects of itopride on GE, glycaemia and upper gastrointestinal symptoms were studied in patients with longstanding diabetes in a randomised, placebo-controlled trial (Chapter 9). There was a trend for itopride to accelerate both solid and liquid GE. 48 % of patients had delayed solid and/or liquid GE on placebo, and in this group, itopride accelerated liquid, but not solid, GE. Autonomic neuropathy represents another pathogenetic factor of diabetic gastroparesis, and delayed GE is more prevalent in patients with autonomic dysfunction. There is evidence that C-peptide improves autonomic nerve function (ANF) in type 1 diabetes. The effects of C-peptide on GE and ANF were studied in patients with longstanding type 1 diabetes in randomised, placebo-controlled design, in Chapter 10. C-peptide had no effect on solid or liquid GE, or ANF. Gastroparesis, particularly in patients with diabetes, represents an important clinical problem. The studies presented in this thesis have provided fundamental insights into the measurement and determinants of gastric motor function and postprandial glycaemia, and treatment of gastroparesis, however, further studies which assess the complex pathogenesis and pathophysiology of gastroparesis, and which include a larger cohort of patients, are warranted. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1456472 / Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2009

The human stomach is a complex organ with sophisticated function. – The control of delivery of nutrients to the small intestine is tightly regulated, and the patterns and determinants of the associated processes are numerous, complex and interrelated. The presence of nutrients in the small intestine stimulates the release of a number of gastrointestinal hormones, including glucagon-like peptide-1 (GLP-1). Exogenous GLP-1 reduces fasting and postprandial glucose concentrations, and this is thought to be via a slowing of gastric emptying (GE). The effects of endogenous GLP-1 on GE and glycaemia were evaluated using exendin(9-39), a GLP-1 antagonist, in healthy subjects, in a randomised, placebo-controlled study, in Chapter 5. Exendin(9-39) increased postprandial glycaemia through an acceleration of GE; these findings support the putative role of GLP-1 as an enterogastrone. The capacity to measure GE has greatly increased the understanding of normal and disordered gastric physiology. 30 – 50 % of patients with longstanding diabetes have delayed GE. Scintigraphy remains the ‘gold standard’ in the measurement of GE, however, it is associated with a radiation burden. Recently, three-dimensional (3D) ultrasonography was validated against scintigraphy in healthy subjects. In Chapter 6, GE was measured concurrently by 3D ultrasonography and scintigraphy in patients with diabetic gastroparesis, and good correlation and agreement was found between both techniques. Glycaemic control represents one of the main pathogenetic factors of diabetic gastroparesis. Hyperglycaemia slows, while hypoglycaemia accelerates, GE in healthy subjects and patients with uncomplicated type 1 diabetes. Chapter 7 reports a study investigating the effects of insulin-induced hypoglycaemia vs. euglycaemia on GE in longstanding type 1 diabetes. Hypoglycaemia accelerated GE of a mixed solid/liquid meal; the magnitude of this acceleration was greater when GE during euglycaemia was slower. In contrast to glucose, the effects of intravenous (iv) fructose (used widely in the diabetic diet) on GE are less well understood. The comparative effects of iv fructose, glucose and saline on GE and antropyloroduodenal motility in healthy males are reported in Chapter 8. Compared with saline, fructose infusion was associated with a slowing of GE and suppression of antral waves, the magnitude of which was comparable to glucose. Treatment for the management of gastroparesis is currently suboptimal and there is a need for novel prokinetic agents. Itopride has demonstrated prokinetic activity in dogs. The effects of itopride on GE, glycaemia and upper gastrointestinal symptoms were studied in patients with longstanding diabetes in a randomised, placebo-controlled trial (Chapter 9). There was a trend for itopride to accelerate both solid and liquid GE. 48 % of patients had delayed solid and/or liquid GE on placebo, and in this group, itopride accelerated liquid, but not solid, GE. Autonomic neuropathy represents another pathogenetic factor of diabetic gastroparesis, and delayed GE is more prevalent in patients with autonomic dysfunction. There is evidence that C-peptide improves autonomic nerve function (ANF) in type 1 diabetes. The effects of C-peptide on GE and ANF were studied in patients with longstanding type 1 diabetes in randomised, placebo-controlled design, in Chapter 10. C-peptide had no effect on solid or liquid GE, or ANF. Gastroparesis, particularly in patients with diabetes, represents an important clinical problem. The studies presented in this thesis have provided fundamental insights into the measurement and determinants of gastric motor function and postprandial glycaemia, and treatment of gastroparesis, however, further studies which assess the complex pathogenesis and pathophysiology of gastroparesis, and which include a larger cohort of patients, are warranted. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1456472 / Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2009

Made available in DSpace on 2014-10-09T12:23:28Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:35Z (GMT). No. of bitstreams: 1 00975.pdf: 8447772 bytes, checksum: 57efc3cd214a3c9ef96ce7216cb7dd50 (MD5) / Tese (Doutoramento) / IEA/T / Faculdade de Medicina, Universidade de Sao Paulo - FM/USP

Orientador: José Ricardo de Arruda Miranda / Banca: Madileine Francely Américo / Banca: Wellington Monteiro Machado / Resumo: Distribuição intragástrica de uma refeição (DIR) e esvaziamento gástrico regional são parâmetros importantes que podem estar associados a alterações na motilidade gástrica. No entanto, não há um consenso sobre o tipo de segmentação e o volume da refeição para se avaliar a DIR e o esvaziamento regional. O objetivo desse estudo foi avaliar a DIR de refeições-teste com 60 ml e 180 ml, utilizando três formas diferentes de segmentação gástrica. Doze voluntários saudáveis foram avaliados, randomicamente, duas vezes pela cintilografia, ingerindo 60 ml e 180 ml de iogurte acrescido de 2 mCi de 99mTc-Estanho Coloidal. Cada medida durou 18 minutos com aquisição de 1 Hz e todos os dados analisados em ambiente MatLab (Mathworks Inc.). A segmentação proximal-distal utilizou regiões de interesse (ROIs), onde o contorno do estômago total obtido após a ingestão de 180 ml foi movido e ajustado às outras imagens. A análise de freqüência e amplitude foi realizada empregando Transformada Rápida de Fourier (FFT) e área sob a curva (AUC), respectivamente. Nossos resultados indicam que há diferenças significativas, na distribuição intragástrica de uma refeição semi-líquida, quando se ingere um volume pequeno (60 ml) ou moderado (180 ml). Outra constatação importante é que a distribuição de uma refeição entre os compartimentos proximal e distal foi fortemente influenciada pelo modo como o estômago foi dividido. Os padrões de freqüência dominante variaram de acordo com a segmentação, independente do volume da refeição escolhido. Esse trabalho proporcionou avanços metodológicos ao comparar a influência da segmentação gástrica sobre a distribuição intragástrica de refeições com volumes distintos. As discrepâncias entre as segmentações mostram que os resultados de uma pesquisa e/ou diagnóstico podem ser profundamente influenciados pelo tipo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Intragastric distribution of a meal (IDM) and regional emptying are important parameters that can be associated to alterations in the gastric motility. However, there is a lack of consensus about proximal-distal segmentation and volume of the test meal to evaluate IDM and the regional emptying. The aim of this study was to evaluate IDM with 60 ml and 180 ml, using three different gastric segmentations. Twelve healthy volunteers were assessed, randomly, twice in scintigraphy. The test meal consisted of 60 ml and 180 ml of yogurt to which has added 2 mCi 99mTc-tin colloid. Anterior dynamic (64 · 64 pixels) frames of 1 s were acquired for 18 min and all data were analyzed in MatLab (Mathworks Inc.). The proximal-distal segmentations used regions of interest (ROI), where the outline of the total stomach obtained after the ingestion of 180 ml was moved and fitting to all images. Frequency and amplitude was analyzed using Transformed Fast of Fourier (FFT) and area under the curve (AUC), respectively. Our results indicate significant differences, in the intragastric distribution of a semi-liquid meal, when a small (60 ml) or moderate (180 ml) volume is ingested. An important finding of this study was that IDM between the proximal and distal compartments was influenced strongly by the way as the stomach was divided. The patterns of dominant frequency varied in agreement with the segmentation adopted, independent of the volume of the meal. This work provided methodological progresses when comparing the influence of the gastric segmentation on the intragastric distribution of meals with different volumes. The discrepancies among the segmentations show that the results of a research and/or diagnosis can be deeply influenced by the segmentation adopted, in other words, as the proximal area increases, larger the amount of meal that is kept in the proximal region. In summary, gastrointestinal... (Complete abstract click electronic access below) / Mestre

A avaliação da técnica de cintilografia da perfusão pulmonar foi realizada em 10 cães machos, da raça Rottweiler, radiograficamente normais e soronegativos para dirofilariose, utilizando-se o macroagregado de albumina sérica humana marcado com tecnécio-99m ([99mTc](MAA)) como radiofármaco. Cada animal sedado foi submetido a três diferentes tratamentos, com administração de 50.000, 100.000 e 300.000 partículas de MAA. As imagens obtidas com as doses variadas do radiofármaco, foram comparadas de forma qualitativa e quantitativa, incluindo nesta última a avaliação do índice de perfusão pulmonar e homogeneidade das imagens. Não foram observadas diferenças significativas entre as imagens durante a avaliação visual e cálculo da quantificação relativa da perfusão pulmonar. Porém, o cálculo da uniformidade integral demonstrou diferença significativa na homogeneidade da imagem pulmonar entre as diferentes doses de MAA. Pode-se concluir que existe um aumento na homogeneidade da imagem diretamente relacionado ao número de partículas de magroagregado de albumina injetado, ainda que tal diferença não tenha sido percebida pela análise qualitativa. / The evaluation of pulmonary perfusion scintigraphy technique was accomplished in 10 Rottweiler male dogs, with normal thoracic radiographs and negative for Dirofilaria immitis, using macroaggregated human serum albumin tagged with technetium-99m ([99mTc](MAA)) as radiopharmaceutical. Each sedated animal was subimited to 3 different treatments, with administration of 50.000, 100.000 and 300.000 particles of MAA. The obtained images with diverse radiopharmaceutical doses were qualitative and quantitative compared, including in this the evaluation of radiopharmaceutical distribution and the homogeneity index. There were observed no significative differences between the images during the visual evaluation and calculation of the relative quantification of the lung perfusion. However, the integral uniformity calculation demonstrated significative difference at the homogeneity of the lung image between the different MAA doses. That leads to the conclusion that there is an increase at the images homogeneity directly related to the number of albumin macroaggregated particles injected, though difference has not been realized by the qualitative analysis.

Os mecanismos fisiológicos sofrem mudanças durante o processo de envelhecimento. Dentre as alterações que ocorrem naturalmente durante esse processo, existem os problemas de deglutição. A integridade da deglutição não só garante a manutenção do estado nutricional do paciente mas também protege o trato respiratório contra acidentes como aspiração de conteúdo da orofaringe; por outro lado, suas alterações, muitas vezes somadas a processos patológicos, levam a complicações nutricionais e infecciosas, favorecendo a ocorrência de outras doenças e podendo, até mesmo, levar a quadros irreversíveis. O presente estudo teve por objetivo avaliar a fase orofaríngea da deglutição de pacientes idosos internados na enfermaria da Divisão de Clínica Médica Geral e Geriatria do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo, com ou sem queixas de dificuldade de deglutição, através da avaliação clínica fonoaudiológica e do estudo cintilográfico da deglutição, correlacionando-os. Para tanto, foram avaliados 30 pacientes idosos internados, com idades entre 66 e 94 anos, idade média de 80 anos, selecionados aleatoriamente, sem se considerar suas doenças e a presença ou não de queixas de disfagia, sendo excluídos os pacientes gravemente comprometidos, cujo estado impossibilitava a avaliação clínica e objetiva da deglutição. Além disso, obteve-se dois grupos controle, sendo um constituído por jovens, com idades variando de 21 a 30 anos, idade média de 25 anos e o outro foi constituído por idosos, com idades variando de 60 a 80 anos, idade média de 70 anos. Os voluntários dos grupos controle foram cuidadosamente triados antes da participação no estudo para assegurar que eles não apresentassem histórias de dificuldades para a deglutição e/ou condições médicas que pudessem influenciar a deglutição ou performance motora orofacial e/ou que usassem medicamentos depressores do sistema nervoso central. Para a avaliação funcional da deglutição, os participantes do estudo deglutiram dois bolos de alimentos de 5 ml cada, nas consistências líquida e pastosa. No estudo cintilográfico foram adicionados aos dois bolos, um marcador de radioatividade de fitato coloidal ligado ao tecnécio (99mTc). Os dados da avaliação foram analisados no computador através do protocolo de aquisição da gama-câmara (vision DST) quanto ao trânsito e resíduo oral, trânsito, clearance e resíduo faríngeo e entrada no esôfago proximal. O estudo permitiu concluir que idosos doentes sem queixa de dificuldade de deglutição e sem a presença de doenças que cursam com a disfagia, não apresentam diferença significativa dos parâmetros observados quando comparados com idosos saudáveis; pessoas idosas deglutem mais lentamente quando comparadas com pessoas mais jovens, entretanto essa lentificação permite que idosos deglutam mais seguramente. As mudanças no hábito alimentar de idosos devem ser questionadas por profissionais que trabalham com a população geriátrica e a avaliação fonoaudiológica clínica da deglutição deve fazer parte da definição do diagnóstico diferencial em quadros que sugiram dificuldades de deglutição e, principalmente deve ser imprescindível naqueles que apresentem patologias que cursam com a disfagia; a técnica cintilográfica é sensível a sutis mudanças relacionadas ao trânsito, clearance e resíduo alimentar. / Physiological mechanisms change during the aging process. Among the changes that occur naturally during this process, there are the problems of swallowing. Swallowing integrity not only warrants the maintenance of the patient’s nutritional status, but also protects the respiratory system against accidents like the aspiration of oropharyngeal contents. On the other hand, changes in the swallowing process, often added by other diseases, induces nutritional and infectious complications, favoring the occurrence of other diseases and, even, irreversible clinical pictures. The present study aimed to assess the oropharyngeal phase of swallowing of older persons admitted to the wards of the Division of General Internal Medicine and Geriatric Medicine of the Internal Medicine Department of the School of Medicine of Ribeirão Preto – University of São Paulo, independently of the presence or absence of swallowing complaints, through phonoaudiological clinical evaluation and cintilographic study of swallowing. Thirty elderly patients were studied, with age ranging from 66 to 94 years old, mean age 80 years, randomly selected, without being taken into consideration specific diseases and the presence or absence of swallowing complaints. Severely compromised Patients, whose health status made impossible adequate evaluation, were excluded. Two control groups were composed, one of young volunteers, aged from 21 to 30 years, mean age 25 years and one of elderly volunteers, with age ranging from 60 to 80 years old, mean age 70 years. Volunteers of the control groups were carefully evaluated before participation, to make sure that they did not have swallowing difficulties and/or clinical conditions that could influence swallowing and oral and facial motor performance and did not take medications with central nervous system actions. For functional assessment of swallowing, the study participants swallowed two boluses of 5 ml each, in liquid and syrup consistence. In the cintilographic study, a radioactive tracer (99mTc colloidal phytate) was added to the boluses. Data were analyzed through the gamma-camera acquisition protocol (vision DST) for oral transit and residual, pharyngeal transit, clearance time and residual and time for proximal esophagus entrance. The study allowed us to conclude that older patients without swallowing complaints and without diseases that cause dysphagia, do not show significant differences of the observed parameters when compared to healthy older persons. Older persons swallow slower when compared to younger persons, however this delay allows them to swallow safer. Changes in dietary habits of older persons should be questioned by professionals that work with geriatric populations and clinical phonoaudiological assessment of swallowing must be part of the assessment process of situations where difficulties for swallowing appeared, being absolutely necessary for those that present diseases that courses with dysphagia. The cintilographic technique is sensitive to subtle changes in transit, clearance and food residuals.