Criação e validação de valores de referência para semiquantificação em exames de SPECT com 123I-FP- CIT para o Hospital Infanta Cristina em Badajoz

Semiquantificação (SQ) nos exames de O DaTScanTM pode apresentar vantagens no diagnóstico de Síndromes Parkinsonianos (SP), especialmente quando os valores utilizados para referência da SQ são adaptados ao serviço em causa. Objetivo do estudo - Criação e validação de bases de dados e valores de referência (VR) adaptados na SQ para diagnóstico de SP recorrendo ao de DaTScanTM, adaptados para o Hospital Infanta Cristina em Badajoz.

A reconstrução tomográfica em SPECT com utilização dos novos métodos iterativos “WBR”: comparação com métodos analíticos

Os métodos utilizados pela Medicina moderna no âmbito da Imagem Molecular e na sua capacidade de diagnosticar a partir da “Função do Orgão” em vez da “Morfologia do Orgão”, vieram trazer á componente fundamental desta modalidade da Imagiologia Médica – A Medicina Nuclear – uma importância acrescida, que se tem traduzido num aumento significativo no recurso á sua utilização nas diferentes formas das suas aplicações clínicas. Para além dos aspectos meramente clínicos, que só por si seriam suficientes para ocupar várias dissertações como a presente; a própria natureza desta técnica de imagem, com a sua inerente baixa resolução e tempos longos de aquisição, vieram trazer preocupações acrescidas quanto ás questões relacionadas com a produtividade (nº de estudos a realizar por unidade de tempo); com a qualidade (aumento da resolução da imagem obtida) e, com os níveis de actividade radioactiva injectada nos pacientes (dose de radiação efectiva sobre as populações). Conhecidas que são então as limitações tecnológicas associadas ao desenho dos equipamentos destinados á aquisição de dados em Medicina Nuclear, que apesar dos avanços introduzidos, mantêm mais ou menos inalteráveis os conceitos base de funcionamento de uma Câmara Gama, imaginou-se a alteração significativa dos parâmetros de aquisição (tempo, resolução, actividade), actuando não ao nível das condições técnico-mecânicas dessa aquisição, mas essencialmente ao nível do pós-processamento dos dados adquiridos segundo os métodos tradicionais e que ainda constituem o estado da arte desta modalidade. Este trabalho tem então como objectivo explicar por um lado, com algum pormenor, as bases tecnológicas que desde sempre têm suportado o funcionamento dos sistemas destinados á realização de exames de Medicina Nuclear, mas sobretudo, apresentar as diferenças com os inovadores métodos, que aplicando essencialmente conhecimento (software), permitiram responder ás questões acima levantadas.

Reconstrução de Imagem em SPECT utilizando um colimador convergente e detectores de imagem pixelizados

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

Functional brain perfusion evaluation with Arterial Spin Labeling at 3 Tesla

Dissertation submitted in Faculdade de Ciências e Tecnologia of Universidade Nova de Lisboa for the degree of Master of Biomedical Engineering

Low coronary perfusion pressure is associated with endocardial fibrosis in a rat model of volume overload cardiac hypertrophy

Left ventricular hypertrophy following volume overload is regarded as an example of cardiac remodeling without increased fibrosis accumulation. However, infarction is associated with increased fibrosis within the noninfarcted, hypertrophied myocardium, particularly in the subendocardial regions. It is conceivable to suppose that, as also occurs postinfarction, low coronary driving pressure may also interfere with accumulation of myocardial fibrosis following aortocaval fistula. PURPOSE: To investigate the role of acute hemodynamic changes in subsequent deposition of cardiac fibrosis in response to aortocaval fistula. METHOD: Aortocaval fistula were created in 4 groups of Wistar rats that were followed over 4 and 8 weeks: aortocaval fistula 4 and aortocaval fistula 8 (10 rats each) and their respective controls (sham-operated controls - Sh), Sh4 and Sh8 (8 rats each). Hemodynamic measurements were performed 1 week after surgery. Hypertrophy and fibrosis were quantified by myocyte diameter and collagen volume fraction at the end of follow up. RESULT: Compared with Sh4 and Sh8, pulse pressure, left ventricular end-diastolic pressure, and +dP/dt were higher in aortocaval fistula 4 and aortocaval fistula 8, but -dP/dt was similar. Coronary driving pressure (mm Hg), used as an estimate of perfusion pressure, was lower in aortocaval fistula 8 (52.6 ± 4.1) than in Sh8 (100.8 ± 1.3), but comparable between aortocaval fistula 4 (50.0 ± 8.9) and Sh4 (84.8 ± 2.3). Myocyte diameter was greater in aortocaval fistula 8, whereas interstitial and subendocardial fibrosis were greater in aortocaval fistula 4 and aortocaval fistula 8. Coronary driving pressure correlated inversely and independently with subendocardial fibrosis (r² = .86, P <.001), whereas left ventricular systolic pressure (r² = 0.73, P = .004) and end-diastolic pressure (r² = 0.55, P = 012) correlated positively and independently with interstitial fibrosis. CONCLUSION: Coronary driving pressure falls and ventricular pressures increase early after aortocaval fistula and are associated with subsequent myocardial fibrosis deposition.

DOTA-based Ga(III) and Gd(III) chelates for medical imaging (PET, SPECT and MRI)

PhD Thesis in Sciences Specialization in Chemistry

Myocardial perfusion by contrast echocardiography. Establishment of normal pattern of intracoronary injection and safety in humans

OBJECTIVE: To establish the normal pattern and safety of echocardiographic contrast in patients with no significant obstruction of epicardial coronary arteries. METHODS: 67 patients with normal coronary arteries or obstructions < 50% were selected from 277 patients who underwent coronary angiography (CA). Mean age was 56 ± 11years and 36 were males. At the end CA, echocardiographic contrast was selectively injected into each coronary artery. The parasternal short axis of the left ventricle (LV) was divided into six segments: anterior (A), antero-lateral (AL), postero-lateral (PL), posterior (P), infero-septal (IS) and antero-septal (AS). Anterolateral (ALPM) and posteromedial papillary muscles (PMPM) were also considered. The pattern and intensity of the appearance of the myocardial contrast was visually analyzed. RESULTS: The right coronary artery (RCA) was dominant in 60 patients. Contrast appearance was sudden and simultaneous in the 3 muscle layers. All segments could be contrasted after the injection in both coronary arteries. 100% of the AS, A and AL segments, 97% of the PL and 98% of the ALPM were perfused by the left coronary artery (LCA). P and IS segments were perfused by the RCA in 85% and 82%, respectively, and by a dominant LCA in 71% of the cases. The PMPM was perfused by a dominant RCA in 77% and by a dominant LCA in 86%. There were no symptoms. CONCLUSION: Intracoronary injection of the sonicated solution is a safe procedure that allows for an excellent opacification of the myocardium and can potentially be used during routine CA.

Assessment of splanchnic perfusion with gastric tonometry in the immediate postoperative period of cardiac surgery in children

OBJECTIVE - A prospective, nonrandomized clinical study to assess splanchnic perfusion based on intramucosal pH in the postoperative period of cardiac surgery and to check the evolution of patients during hospitalization. METHODS - We studied 10 children, during the immediate postoperative period after elective cardiac surgery. Sequential intramucosal pH measurements were taken, without dobutamine (T0) and with 5mcg/kg/min (T1) and 10 (T2) mcg/kg/min. In the pediatric intensive care unit, intramucosal pH measurements were made on admission and 4, 8, 12, and 24 hours thereafter. RESULTS - The patients had an increase in intramucosal pH values with dobutamine 10mcg/kg/min [7.19± 0.09 (T0), 7.16±0.13(T1), and 7.32±0.16(T2)], (p=0.103). During the hospitalization period, the intramucosal pH values were the following: 7.20±0.13 (upon admission), 7.27±0.16 (after 4 hours), 7.26±0.07 (after 8 hours), 7.32±0.12 (after 12 hours), and 7.38±0.08 (after 24 hours), (p=0.045). No deaths occurred, and none of the patients developed multiple organ and systems dysfunction. CONCLUSION - An increase in and normalization of intramucosal pH was observed after dobutamine use. Measurement of intramucosal pH is a type of monitoring that is easy to perform and free of complications in children during the postoperative period of cardiac surgery.

Neonate Aortic Stenosis: Importance of Myocardial Perfusion in Prognosis

OBJECTIVE: To analyze our experience with percutaneous aortic balloon valvuloplasty in newborn infants with aortic stenosis, emphasizing the extraordinary importance of myocardial perfusion.METHODS: Over a 10-year-period, 21 neonates underwent percutaneous aortic balloon valvuloplasty. Age ranged from 2 to 27 days, weight ranged from 2.2 to 4.1 kg and 19 were males. All patients presented with congestive heart failure that could not be treated clinically. The onset of symptoms in the first week of life occurred in 9 patients considered as having critical aortic stenosis. Severe aortic stenosis occurred in 12 patients with the onset of symptoms in the second week of life.RESULTS: Mortality reached 100% in the patients with critical aortic stenosis. The procedure was considered effective in the 12 patients with severe aortic stenosis. Vascular complications included the loss of pulse in 12 patients and rupture of the femoral artery in 2 patients. Cardiac complications included acute aortic regurgitation in 2 patients and myocardial perforation in one. In an 8.2±1.3-year follow-up, 5 of the 12 patients died (2 patients due to septicemia and 3 patients due to congestive heart failure). Five of the other 7 patients underwent a new procedure and 2 required surgery.CONCLUSION: Percutaneous aortic valvuloplasty in neonates is not an effective procedure in the 1st week of life, because at this age the common presentation is cardiogenic shock. It is possible that, in those patients with critical aortic stenosis, dilation of the aortic valve during fetal life may change the prognosis of its clinical outcome.

Prognostic value of technetium-99m-labeled single-photon emission computerized tomography in the follow-up of patients after their first myocardial revascularization surgery

OBJECTIVE: To assess the prognostic value of Technetium-99m-labeled single-photon emission computerized tomography (SPECT) in the follow-up of patients who had undergone their first myocardial revascularization. METHODS: We carried out a retrospective study of 280 revascularized patients undergoing myocardial scintigraphy under stress (exercise or pharmacological stress with dipyridamole) and at rest according to a 2-day protocol. A set of clinical, stress electrocardiographic and scintigraphic variables was assessed. Cardiac events were classified as "major" (death, infarction, unstable angina) and "any" (major event or coronary angioplasty or new myocardial revascularization surgery). RESULTS: Thirty-six major events occurred as follows: 3 deaths, 11 infarctions, and 22 unstable anginas. In regard to any event, 22 angioplasties and 7 new surgeries occurred in addition to major events, resulting a total of 65 events. The sensitivity of scintigraphy in prognosticating a major event or any event was, respectively, 55% and 58%, showing a negative predictive value of 90% and 83%, respectively. Diabetes mellitus, inconclusive stress electrocardiography, and a scintigraphic visualization of left ventricular enlargement were significant variables for the occurrence of a major event. On multivariate analysis, abnormal myocardial scintigraphy was a predictor of any event. CONCLUSION: Myocardial perfusion tomography with Technetium-99m may be used to identify high-risk patients after their first myocardial revascularization surgery.

Diferenças relacionadas ao sexo nos volumes ventriculares e na fração de ejeção do ventrículo esquerdo estimados por cintilografia de perfusão miocárdica: comparação entre os programas Quantitative Gated SPECT (QGS) e Segami

OBJETIVO: Analisar as diferenças relacionadas ao sexo nas medidas obtidas pelos programas Segami e Quantitative Gated SPECT (QGS). MÉTODOS: Cento e oitenta e um indivíduos assintomáticos sem evidência de cardiopatia foram submetidos a estudos de perfusão miocárdica. O volume diastólico final (VDF), volume sistólico final (VSF) e a fração de ejeção do ventrículo esquerdo (FEVE) foram quantificados pelos programas QGS and Segami para avaliar a influência do sexo, idade, peso, altura, freqüência cardíaca, pressão arterial sistólica, pressão arterial diastólica, índice de massa corporal e área de superfície corporal. RESULTADOS: As médias obtidas com o método QGS foram VDF (mulheres = 68 ml; homens = 95 ml; p < 0,001) e FEVE (mulheres = 66,24%; homens = 58,7%), e com o Segami, VDF (mulheres = 137 ml; homens = 174 ml) e FEVE (mulheres = 62,67%; homens = 58,52%). Foram observadas diferenças significantes entre homens e mulheres no VDF (p < 0,001) e VSF (p < 0,001), que persistiram após o ajuste em relação à área de superfície corporal. CONCLUSÃO: Os volumes ventriculares foram significantemente menores e a FEVE foi significantemente maior em mulheres, de acordo com os programas QGS e Segami.