Alzheimer’s disease (AD) is the leading cause of dementia and is alone responsible for 60-70% of all cases of dementia. Though sharing clinical symptoms with other types of dementia, the hallmarks of AD are the abundance of extracellular depositions of β-amyloid (Aβ) plaques, intracellular neurofibrillary tangles of hyper phosphorylated tau proteins and synaptic depletion. The onset of the physiological hallmarks may precede clinical symptoms with a decade or more, and once clinical symptoms occur it may be difficult to separate AD from other types of dementia based on clinical symptoms alone. Since the introduction of radiolabeled Aβ tracer substances for positron emission tomography (PET) imaging it is possible to image the Aβ depositions in-vivo, strengthening the confidence in the diagnosis. Because the accumulation of Aβ may occur years before the first clinical symptoms are shown and even reach a plateau, Aβ PET imaging may not be feasible for disease progress monitoring. However, a negative scan may be used to rule out AD as the underlying cause to the clinical symptoms. It may also be used as a predictor to evaluate the risk of developing AD in patients with mild cognitive impairment (MCI) as well as monitoring potential effects of anti-amyloid drugs.Though currently validated for dichotomous visual assessment only, there is evidence to suggest that quantification of Aβ PET images may reduce inter-reader variability and aid in the monitoring of treatment effects from anti-amyloid drugs.The aim of this thesis was to refine existing methods and develop new ones for processing, quantification and visualization of Aβ PET images to aid in the diagnosis and monitoring of potential treatment of AD in clinical routine. Specifically, the focus for this thesis has been to find a way to fully automatically quantify and visualize a patient’s Aβ PET image in such way that it is presented in a uniform way and show how it relates to what is considered normal. To achieve the aim of the thesis registration algorithms, providing the means to register a patient’s Aβ PET image to a common stereotactic space avoiding the bias of different uptake patterns for Aβ- and Aβ+ images, a suitable region atlas and a 3-dimensional stereotactic surface projections (3D SSP) method, capable of projecting cortical activity onto the surface of a 3D model of the brain without sampling white matter, were developed and evaluated.The material for development and testing comprised 724 individual amyloid PET brain images from six distinct cohorts, ranging from healthy volunteers to definite AD. The new methods could be implemented in a fully automated workflow and were found to be highly accurate, when tested by comparisons to Standards of Truth, such as defining regional uptake from PET images co-registered to magnetic resonance images, post-mortem histopathology and the visual consensus diagnosis of imaging experts.

No description available.

Cerebral small vessel disease (SVD) is identifiable by clinical, neuroimaging, neuropathological and cognitive findings. The aim of this thesis was to assess SVD and cerebral perfusion on magnetic resonance imaging (MRI) in a 75-year-old population and compare the findings with scars of myocardial infarctions, cardiovascular risk markers and cognitive function. In addition, the evolution of SVD over 5 years was studied. The study population included subjects from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. The subjects had been chosen in a randomized manner from the register of the municipality. MRI of the brain and the heart, cognitive tests and blood tests for cardiovascular risk factors were performed in 406 subjects at age 75 years and 250 of them were re-examined 5 years later at the age of 80. Paper 1 showed that unrecognized myocardial infarctions (UMIs) were found in 120 subjects (30%) and recognized myocardial infarctions (RMIs) in 21 (5%). Men with RMIs displayed an increased prevalence of cortical and lacunar cerebral infarctions, whereas women with UMIs more frequently had cortical cerebral infarctions. Paper 2 showed that one or more brain infarcts were seen in 23% of the subjects (20% had only lacunar infarcts, 1% had only cortical infarcts and 2% had both). Hypertension and obesity were significantly associated with an increased risk of infarction.  The newer risk markers investigated were not significantly associated with brain infarcts. Paper 3 showed that MRI manifestations of SVD progressed over 5 years. Relative cerebral blood flow (rCBF) was not associated with WMH volume or progression of WMH volume. Paper 4 showed that moderate to severe WMHs and incident lacunar infarcts on brain MRI were associated with a mild impairment of executive function. In conclusion, this longitudinal population based study compares MRI manifestations of SVD with clinical data, providing knowledge that may be used in further investigations of preventive interventions and for identification of disease in early stages.

The aim of this diploma thesis is to analyse health and safety system in department of nuclear medicine in Kolín hospital and evaluate its compliance with czech legislation. The thesis is compsed of four chapters. Chapter One gives a general introduction to health and safety issues and describes most important aspect of general health and safety legislation. Chapter Two explains the basic terms of ionizing radiation and radioactivity and focuses mainly on radiation protection, which is closely linked to the health and safety area. Chapter Three defines the legislative and institutional framework of health and safety in the area of ionizing radiation. This chapter is a starting point for Chapter Four, which analyzes the health and safety system in department of nuclear medicine in Kolín hospital, compares it with legislation requirements and evaluates the compliance.

Bakgrund: Vissa av röntgensjuksköterskans arbetsuppgifter kan utföras av andra professioner som sjuksköterska eller undersköterska detta kallas för jobbglidning mellan yrkesroller. Jobbglidning kan ske på grund av många olika orsaker som brist på personal, ökad befolkning vilket gör att mer personal behövs inom vården. Att undersköterska eller sjuksköterska utför vissa av röntgensjuksköterskans arbetsuppgifter kan påverka patientsäkerheten. Syfte: Att undersöka röntgensjuksköterskors syn på att arbetsuppgifter inom professionen utförs av sjuksköterska eller undersköterska. Metod: En kvantitativ enkätstudie med 53 deltagare som är legitimerade röntgensjuksköterskor från fyra sjukhus i två olika regioner. Resultat: Majoriteten av deltagarna anser att det är negativt att sjuksköterskor utför arbetsuppgifter inom mammografi och angiografi. Medan flera av deltagarna tycker det är bra om sjuksköterskor kan beräkna GFR inför undersökningar. Deltagarna anser att det är dåligt om undersköterskor utför konventionella röntgenundersökningar och att ge information om kontrastmedel till patienten medan de anser att det var mycket bra om undersköterskor tar in patienter på undersökningsrummet. Slutsats: Studien visar att röntgensjuksköterskorna generellt har negativ syn på att lämna deras arbetsuppgifter till de andra professionerna, utan de vill behålla deras kompetens inom områden som angiografi, mammografi och konventionell röntgen.

O estudo de processos inflamatórios e infecciosos em Medicina Nuclear apresenta grande relevância para a clínica médica diagnostica. Enquanto em alguns casos o diagnóstico é óbvio, baseado na história clínica e exame físico do paciente, em outros é mais difícil, por serem assintomáticos ou por apresentarem sintomas não específicos. O diagnóstico precoce do processo inflamatório ou infeccioso permite tratamento rápido e também o impedimento de outras complicações. Além disto, a distinção entre inflamação e infecção é de extrema importância, bem como a provável localização. O uso de leucócitos radiomarcados, já estudados e aplicados em várias patologias, é o método de escolha para visualização de focos de infecção e inflamação. A cintilografia de leucócitos radiomarcados foi introduzida em 1976 por McAffe e Thakur e desde então é usada para diagnosticar diferentes patologias que envolvem infiltração leucocitária como distúrbios inflamatórios do intestino, infecção óssea ou prótese-vasculares entre outras. A marcação dos leucócitos in vitro pode ser realizada com 111In utilizando-se oxima ou tropolona como ligante ou com 99mTc, tendo a hexametilpropileno amino oxima (HMPAO) como ligante, resultando em um complexo lipofílico. A melhor disponibilidade, menor tempo de realização do exame, melhor propriedade física e menor dose de radiação para o paciente, resultou na preferência pelo agente HMPAO marcado com 99mTc, ao invés do 111In, para a maioria das indicações na maioria dos países. Entretanto, a marcação empregando o agente HMPAO apresenta como desvantagens a curta estabilidade do reagente marcado, as exigências relacionadas ao processo de marcação (tempo pós-eluição do 99mTc), além do custo elevado, pois se trata de produto importado. Este trabalho visou o desenvolvimento do reagente liofilizado de glucoheptonatoestanho para marcação de leucócitos com 99mTc in vitro pelo método de préestanização. A otimização da técnica de marcação foi realizada através da incubação dos leucócitos, isolados de sangue total, com diferentes volumes do reagente de glucoheptonato-estanho por diferentes tempos à 37°C (préestanização), com posterior marcação com 99mTc (185 MBq), incubados à temperatura ambiente por 20 minutos. O rendimento da marcação foi superior a 90% na condição ótima de marcação. O reagente liofilizado mostrou-se estável por mais de 90 dias. As imagens cintilográficas obtidas 1, 2 e 3 horas após a administração dos leucócitos radiomarcados em coelho New Zeland demonstraram a alta eficiência de marcação de processo inflamatório provocado a partir da administração local de terebentina. O método de marcação de leucócitos desenvolvido apresenta aplicação promissora na clínica médica, com proposta de redução de custo do procedimento, apesar de ser um procedimento mais demorado quando comparado ao procedimento que utiliza o quelante lipofílico de HMPAO. / The study and localization of inflammatory and infection process in Nuclear Medicine represents a relevant tool in diagnostic procedures. In same cases, the diagnostic is easy and based on anamnesis and clinical observation; in other cases, the patients are asymptomatic or present non specific symptoms that difficult the diagnostic. The early diagnostic of inflammatory or infectious process allow the early introduction of therapy and prevents complications. Farther, the differentiation between inflammation and infection is of extreme importance as well as the localization of the focus. The use of labeled leucocytes, studied and applied in much pathologies, is the method of choice for the visualization of inflammation and infection. The scintigraphy using labeled leucocytes was introduced at 1976 by McAffe and Thakur and since of this is used in the diagnostic of different pathologies related to leucocyte infiltration like intestinal inflammatory disease, bone or prosthetic-vascular infections. The in vitro labeling of leucocytes with 111In was performed using oxime or tropolone as ligand and with 99mTc using hexamethylpropylene amine oxime (HMPAO) as ligand, resulting in a lipophilic complex. The 99mTc-HMPAG complex was preferably employed in many indications and countries do to the ideal physical properties of 99mTc that results in low dose to the patient. However, the labeling employing the HMPAO complex results in some disadvantages like the low stability of the complex, and some requirements related to the 99mTc elution (like the time pos elution), beyond the high cost of the compound that is imported. The aim of this work was the development of a tin-glucoheptonate lyophilized kit for in vitro leucocytes labeling with 99mTc using the pre-stannization method. The optimization of the labeling technique was developed using leucocytes isolated from total blood and employing different volumes of the tinglucoheptonate reagent and different incubation times at 37 deg C (pre-stannization), and posterior labeling with 99mTc (185 MBq), after 20 minutes reaction at room temperature. The labeling yield was superior to 90% using the optimized labeling conditions. Lyophilized reagent was stable after 90 days. Scintilographic images obtained 1, 2 e 3 hours after the administration of labeled leucocytes in New Zealand rabbit, showed good uptake on inflammatory focus promoted by tupertine injection. The leucocytes labeling method developed can be probably applied in clinical procedures and represents cost effective method in substitution of the lipophilic complex of HMPAO.

A tomografia por emissão de pósitrons (\"Positron Emission Tomography\" - PET) é uma técnica para obtenção de imagens tomográficas em Medicina Nuclear que permite o estudo da função e do metabolismo do corpo humano em diversos problemas clínicos, através do uso de fármacos marcados por radionuclídeos emissores de pósitrons. As aplicações mais frequentes ocorrem em oncologia, neurologia e cardiologia, através da análise qualitativa e quantitativa dessas imagens. Atualmente, a PET é realizada de duas maneiras: através de sistemas constituídos por anéis formados por alguns milhares de detectores operando em coincidência, chamados de sistemas dedicados; ou com o uso de câmaras PET /SPECT, formadas por dois detectores de cintilação em coincidência, que também servem para estudos com radionuclídeos emissores de fóton único (\"Single Photon Emission Computed Tomography\" - SPECT). O desenvolvimento desses sistemas PET /SPECT tornou viáveis os estudos com a fluor-deoxiglicose, [18 ANTPOT. F]-FDG, um fármaco marcado com 18 ANTIPOT. F (emissor de pósitrons com 109 minutos de meia-vida física), para um número grande de clínicas e hospitais, principalmente por estes serem de uma tecnologia economicamente mais acessível que os realizados com a PET dedicada. Neste presente trabalho, desenvolveu-se uma metodologia para caracterizar e avaliar um sistema PET /SPECT com dois detectores de cintilação e dispositivo com duas fontes pontuais de Cs-137, destinado à obtenção das imagens de transmissão para a correção de atenuação dos fótons. Ela se baseia em adaptações dos testes convencionais de câmaras SPECT, descritos no IAEA TecDoc - 602 - 1991 (\"lnternational Atomic Energy Agency\" - IAEA), e de sistemas PET dedicados, publicados no NEMA NU 2- 1994 (\"National Electrical Manufacturers Association\"NEMA). O resultado foi organizado em forma de roteiros que foram testados em uma câmara da ADAC Laboratories/Philips, a VertexlM - Plus EPIClMJMCDlM - AC, instalada no Serviço de Radioisótopos do lnCor - HCFMUSP (Instituto do Coração - Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo). Esta câmara foi a primeira instalada no Brasil e está sendo utilizada, predominantemente, para estudos oncológicos e de viabilidade miocárdica. O radiofármaco utilizado na obtenção das imagens foi a [18F]-FDG, fornecida regularmente pelo IPEN/CNEN-SP (Instituto de Pesquisas Energéticas e Nucleares/Comissão Nacional de Energia Nuclear - São Paulo), e a reconstrução tomográfica foi realizada com o software próprio do sistema, utilizando-se os parâmetros padrão dos protocolos clínicos. Foram utilizadas fontes pontuais suspensas no ar para as medidas de resolução espacial transversal e lineares imersas na água para as de fração de espalhamento e sensibilidade. Na avaliação da sensibilidade, uniformidade, taxa de eventos verdadeiros, taxa de eventos aleatórios e tempo morto do sistema eletrônico, foram feitas imagens de um simulador físico construído especialmente para o presente trabalho, a partir das instruções da publicação NEMA NU 2 - 1994 para sistemas PET dedicados. A acurácia da correção de atenuação foi verificada através das imagens do simulador físico citado com a inserção de três cilindros de densidades diferentes: água, ar e Teflon. Os roteiros deste trabalho poderão servir de guia para Programas de Controle e Garantia de Qualidade e avaliação da performance de sistemas PET /SPECT com dois detectores de cintilação em coincidência. A implantação destes roteiros pelos centros clínicos que utilizam este tipo de equipamento aumentará a qualidade e a confiabilidade nas imagens resultantes, assim como na sua quantificação. / Positron emission tomography, PET, is a Nuclear Medicine technique that allows the study of human body\'s function and metabolism in many clinical problems, with the help of pharmaceuticals labeled with positron emitters. The most frequent applications occur in oncology, neurology and cardiology, through qualitative and quantitative analysis of these images. Currently, PET is performed in two manners: by using dedicated systems, consisted of rings of thousands of detectors operating in coincidence; or with the use of PET /SPECT cameras, formed by two scintillation detectors in coincidence, which are also used in SPECT studies (single photon emission tomography). The development of PET /SPECT systems made possible the studies with fluor-deoxiglucose, [18F]-FDG, a pharmaceutical labeled with 18F (positron emitter with 109 minutes physical half-life), for a large number of clinics and hospitals, mainly due to their economical accessibility when compared to the dedicated PET studies. In this present work, a method was developed for characterizing and evaluating a PET /SPECT system with two scintillation detectors and device with two point sources of 137Cs, designed to obtain the transmission images for the photon attenuation correction. lt is based on adaptations of the conventional tests of SPECT cameras, described in IAEA TecDoc - 602 - 1991 (\"international Atomic Energy Agency \" - IAEA), and those for dedicated PET systems, published in NEMA NU 2 - 1994 (\"National Electrical Manufacturers Association \" - NEMA). The results were organized in a set of testing protocols and tested in the ADAC Laboratories/Philips camera, the VertexlM - Plus EPIClM/MCDlM - AC, installed in the Radioisotopes Service of lnCor - HCFMUSP (Instituto do Coração - Hospital das clínicas da Faculdade de Medicina da Universidade de São Paulo). This camera was the first one installed in Brazil and is being used, predominantly, for oncological studies and miocardial viability. The radiopharmaceutical used was [18F]-FDG, supplied regularly by IPEN/CNEN-SP (Instituto de Pesquisas Energéticas e Nucleares I Comissão Nacional de Energia Nuclear - São Paulo), and the tomographic reconstruction was performed with the system software, using the standard parameters of the clinical protocols. Point sources suspended in air were used in the measurements of spatial resolution and linear sources immersed in water for scattering fraction and sensitivity measurements. In the evaluation of sensitivity, uniformity, true events, random events and dead time of the electronic system, a phantom was constructed specifically for the present work, from the instructions of NEMA NU 2 - 1994 for dedicated PET systems. The accuracy of the attenuation correction was verified from the images of the phantom with three inserts of different densities: water, air and Teflon. The resultant protocols can serve as a guideline for Programs of Quality Control and Assurance, as well as for the evaluation of the performance of PET /SPECT systems with two scintillation detectors in coincidence. lf implemented by clinical centers that use this type of equipment, it will enhance the quality and confidence of the resulting images, as well as their quantification.

Die nicht-invasive bildgebende Diagnostik hat bei koronarer Herzkrankheit einen wichtigen Stellenwert für die Diagnosestellung und Therapieplanung. In diesem Zusammenhang liefern nuklearmedizinische Verfahren wichtige Daten zur Gewebsperfusion und erlauben die bildliche Darstellung und Quantifizierung relevanter Details des kardiomyozytären Stoffwechsels. Die quantitativ bedeutendste Methode der nuklearmedizinischen Herzdiagnostik ist die Perfusionsszintigraphie mit Tl-201 oder einem der Tc-99m-markierten Tracer (Sestamibi, Tetrofosmin). Die Perfusionsszintigraphie gibt eine Darstellung der Perfusionsverhältnisse auf zellulärem Niveau während Belastung und Ruhe und erlaubt zusätzlich die Einschätzung der myokardialen Vitalität. Neben der Darstellung der Myokard-Perfusion ist die Untersuchung des myokardialen Energiestoffwechsels von besonderem Interesse, da jegliche Kontraktion auf der Bereitstellung einer ausreichenden Menge energiereicher Phosphate beruht und Störungen des Energiestoffwechsels zu unmittelbaren Konsequenzen für die Kontraktion führen. In der klinischen Diagnostik hat sich die Darstellung des myokardialen Glukosestoffwechsels mit F-18-Fluorodesoxyglukose (FDG) durchsetzen können und gilt als Goldstandard für den Vitalitätsnachweis. Jede Perfusionsstörung wirkt sich unmittelbar auf den myokardialen Energiehaushalt aus. Als Indikator für die Störung des Energiehaushalts kann die veränderte Nutzung unterschiedlicher energieliefernder Substrate dienen. Die Folgen von Koronarstenosen für den kardiomyozytären Energiehaushalt lassen sich demnach durch die veränderte Nutzung radioaktiv markierter Substrate erfassen und bildlich mittels nuklearmedizinischer Methoden darstellen. Während die Darstellung des myokardialen Glukosestoffwechsels bereits Eingang in die klinische Diagnostik gefunden hat, ist die Analyse des kardialen Lipidmetabolismus aufgrund der Komplexität der möglichen Stoffwechselwege schwieriger und bislang ohne klinische Bedeutung. Lipide sind aber - zumindest theoretisch - von besonderem Interesse, da ihre Oxidation einerseits für den Hauptteil der ATP-Produktion verantwortlich ist und andererseits Abbauprodukte aus dem Lipidstoffwechsel zu einer Schädigung des Herzens beitragen können. Das Ziel dieser Arbeit war dementsprechend die Bestimmung der Extraktion langkettiger Fettsäuren in (chronisch) ischämischem (hibernierendem) und in reperfundiertem ("stunned myocardium") Myokard. Als Fettsäure wurde I-123-Iodophenyl-Pentadekansäure verwendet, die vergleichbar mit Palmitinsäure in die Zellen aufgenommen und dann entweder der beta-Oxidation zugeführt oder in intrazelluläre Lipidpools integriert wird. Im ersten Teil der Arbeit erfolgten Experimente mit isolierten Rattenherzen, die flußkonstant nach Langendorff perfundiert wurden. Der Fettsäuremetabolismus wurde mittels Indikator-Verdünnungsmethode untersucht, wobei Tc-99m-Albumin als intravaskulärer Referenztracer diente. Es erfolgten Experimente zur Charakterisierung der Fettsäure-Extraktion während unterschiedlicher Flußraten und während 90minütiger Reperfusion nach 20minütiger Ischämie (Flußreduktion auf 25% des Kontrollwertes). Als Perfusat diente eine modifizierte Krebs-Henseleit-Lösung, der entweder 10 mmol/l Glukose oder 10 mmol/l Glukose + 5 I.E./l Alt-Insulin zugesetzt wurden. Die Ergebnisse der Untersuchungen am isolierten Rattenherz zeigen, daß die Extraktion von Fettsäuren auch in (akut) minderperfundiertem Myokard erhalten ist. Die I-123-IPPA-Extraktion stieg bei Reduktion des Blutflusses zunächst exponentiell und bei Reduktion unter 25% des Kontrollflusses mehr als exponentiell an. Bei Zusatz von Insulin zum Perfusat war die Beziehung zwischen Fluß und Fettsäure-Extraktion qualitativ nicht verändert. Quantitativ ergaben sich Differenzen, die insbesondere das Ausmaß der Nettoextraktion bei hohen Flußraten betrafen (höher bei Zusatz von Insulin). Während Reperfusion hing die Fettsäureextraktion von der Zusammensetzung des Perfusats ab. Bei Insulinzusatz (gute intrazelluläre Glukoseverfügbarkeit) war die Fettsäureextraktion reduziert, ohne Insulinzusatz diskret gesteigert. Die Erholung der Wandbewegung ging der Normalisierung der Fettsäureextraktion zeitlich voraus. Das kapilläre Permeabilitäts-Oberflächen-Produkt (PS-Produkt) für I-123-IPPA war in beiden Perfusatgruppen während Reperfusion deutlich auf 20-30% des Kontrollwerts vermindert. Der Abfall des PS-Produkts ist primär Ausdruck einer Ischämie- (oder Reperfusions-) assoziierten Endothelschädigung mit verminderter Permeabilität für I-123-IPPA. Im zweiten Teil der Arbeit wurden Patienten mit koronarer Herzkrankheit untersucht. Dabei handelte es sich einerseits um Patienten nach akutem Myokardinfarkt mit effektiver Reperfusion ("stunning") und andererseits um Patienten mit chronischer KHK und eingeschränkter linksventrikulärer Funktion ("hibernation"). Die Ergebnisse der Patientenuntersuchungen zeigen (ähnlich wie die Daten der Experimente am isolierten Herzen), daß sich myokardiales stunning und hibernation durch unterschiedliche Muster der Fettsäureverwertung unterscheiden. Chronisch minderperfundiertes Myokard zeigte eine erhaltene Fettsäureextraktion, während die Fettsäureaufnahme in reperfundiertem Myokard vermindert war. In reperfundiertem Myokard überdauerte die Reduktion der Fettsäureextraktion die Störung der regionalen Wandbewegung. Insgesamt zeigen die Ergebnisse der Experimente am isolierten Herzen wie auch der Patientenstudien, daß durch Szintigraphie mit radioaktiv markierten Fettsäuren unterschiedliche ischämische Syndrome (stunning, hibernation) differenziert werden können. Allerdings ist die Störung der Fettsäureextraktion unspezifisches Zeichen einer Myokardschädigung und auch nach Beseitigung des schädigenden Einflußes noch über einen relativ langen Zeitraum nachweisbar. Der potentielle klinische Nutzen der Fettsäureszintigraphie wird erheblich davon abhängen, inwieweit es gelingt, unterschiedliche Fettsäure-Verwertungsmuster mit der individuellen Prognose eines Patienten zu korrelieren. / The most important single procedure in nuclear cardiology is myocardial perfusion imaging with Tl-201 or one of the Tc-99m labeled tracers (sestamibi, tetrofosmin). Perfusion scintigraphy allows the assessment of perfusion on a cellular level during stress and at rest, and of myocardial viability. Besides the assessment of myocardial perfusion, the examination of myocardial energy metabolism is of special interest, because every contraction relies on a sufficient amount of high-energy phosphates and every disturbance of energy metabolism is directly followed by a disturbance of myocardial contraction. In clinical cardiology, imaging of myocardial glucose metabolism with F-18 fluoro-deoxyglucose (FDG) is the accepted gold standard for myocardial viability. Every disturbance of perfusion exerts direct influence on energy metabolism. The altered use of the different energy-yielding substrates can be regarded as an indicator of the degree of metabolic disturbance. Therefore, the consequences of coronary stenoses on energy metabolism can be assessed with radioactive substrates and imaged with nuclear medicine methods. Whereas imaging of glucose metabolism is part of today's clinical cardiology, the analysis of lipid metabolism is - due to the complexity of possible metabolic pathways - more difficult and so far without clinical relevance. However, lipids are of special importance, because (1) their oxidation is responsible for the major part of ATP production and (2) degradation products from the lipid metabolism contribute to cardiac damage. The aims of these studies were to examine the extraction of long-chain fatty acids in chronically ischemic ("hibernating") and in reperfused ("stunned") myocardium. In the experiments, I-123 iodophenylpentadecanoic acid (IPPA) served as labeled long-chain fatty acid. Cellular uptake of IPPA is comparable to palmitic acid and - after uptake - IPPA undergoes either beta-oxidation or is integrated into intracellular lipid pools. The first part of these studies deals with experiments in isolated rat hearts which were subjected to retrograde perfusion according to Langendorff. Fatty acid metabolism was analyzed in these hearts using the indicator-dilution technique with Tc-99m albumin as intravascular reference. Fatty acid extraction was assessed at different flow rates and during reperfusion after flow reduction to 25% of control for 20 min. All hearts were perfused with a modified Krebs-Henseleit solution with the addition of either 10 mmol/l glucose or 10 mmol/l glucose + 5 IU insulin. The results of the isolated rat heart experiments show that the extraction of long-chain fatty acids is preserved in myocardium subjected to (acute) low flow ischemia. IPPA extraction increased exponentially with reduction of blood flow and even showed a more than exponential increase at flow rates below 25% of control. After adding insulin to the perfusate the relation between flow and fatty acid extraction was not altered qualitatively. Quantitatively, differences were detected which primarily refer to a higher net extraction at high flow rates. Fatty acid extraction during reperfusion depended on the composition of the perfusate. After addition of insulin (high intracellular glucose availability) fatty acid extraction was reduced, whereas it was increased without insulin. Recovery of wall motion preceded the normalization of fatty acid extraction. The capillary permeability-surface product (PS product) for IPPA was reduced in both perfusate groups to 20-30% of control. The decrease of the PS product can be primarily attributed to ischemia- and/or reperfusion-associated endothelial damage. The second part of these studies deals with the examination of (1) patients after acute myocardial infarction with effective reperfusion (clinical model of "stunning") and (2) patients with chronic coronary artery disease and reduced left ventricular function ("hibernation"). The results in these patient groups show (comparable to the data of the isolated heart experiments) that myocardial stunning and hibernation can be distinguished by different patterns of fatty acid utilization. Fatty acid extraction was preserved in chronically hypoperfused myocardium, whereas it was reduced in reperfused segments. In reperfused myocardium, the reduction of fatty acid extraction outlasted the wall motion abnormality. In conclusion, the results show that scintigraphy with radio-labeled long chain fatty acids can distinguish between different ischemic syndromes (stunning, hibernation). However, the alteration of fatty acid extraction is an unspecific sign of cardiac damage which persists after removal of the harmful stimulus. The potential clinical benefit of fatty acid scintigraphy will largely depend on the definition of different fatty acid utilization patterns and the correlation of these utilization patterns with the prognosis of individual patients.

Nenhuma / Os procedimentos médicos de diagnóstico e tratamento que utilizam radiofármacos geram rejeitos radioativos que, após decaírem até o limite de eliminação, podem ser destinados pelas vias convencionais de coleta e disposição final de Resíduos Sólidos Urbanos RSU. O objetivo da pesquisa foi detectar radiometricamente a presença de rejeitos radioativos nos resíduos de serviços de saúde destinados à disposição final. Ressalta-se que o limite legal de eliminação para rejeitos sólidos estabelecido pela Comissão Nacional de Energia Nuclear CNEN é de 7,5 x 104 Bq/kg (2 Ci/kg). As medições foram feitas no conteúdo de 25 caminhões da coleta especial de Resíduos de Serviços de Saúde (RSS), no aterro sanitário de Belo Horizonte, utilizando-se um cintilômetro de iodeto de sódio. Em 60% dos casos foram encontrados valores acima do limite estabelecido. A análise espectral de 6 amostras revelou a presença do radionuclídeo tecnécio-99m (99mTc), em 5 delas, e de eodo-131 (131I), em um caso. Estes elementos, tecnécio-99m (99mTc) e iodo-131 (131I), são os mais utilizados em procedimentos de Medicina Nuclear. Conclui-se que está havendo liberação de rejeito radioativo com os de Resíduos de Serviços de Saúde (RSS), devido a inobservância do tempo de decaimento até obtenção dos níveis legalmente permitidos para liberação. / The medical procedures of diagnosis and treatment that use radiopharmaceuticals generate radioactive wastes that can, after reaching the release limit, follow the conventional ways of collection and disposal of the urban solid wastes. This research aims to detect radiometrically the presence of radioactive wastes in the health-care wastes at the final disposal. It is pointed out that the legal limit for the release of solid wastes established by Brazilian National Commission of Nuclear Energy (CNEN) is 7,5x104 Bq/kg (2 Ci/kg). Measurements in the material of the garbage trucks that make the special collect from Health Service installations are performed, at Belo Horizonte sanitary landfill, using a NaI scintillation counter. Values above the established limit were found in 60% of the cases. The spectral analysis of 6 samples showed the presence of 99mTc in 5 of them and 131I in one. These radionuclides are the most common radionuclides used in Nuclear Medicine. In conclusion there are radioactive wastes released together with the health service wastes, due to the disregard of the decay time until the legal limit is achieved.

Nenhuma / O desenvolvimento e a consolidação de novas tecnologias na radiologia vêm se constituindo em uma estratégia permanente das empresas, uma vez que resulta em ganhos de produtividade, qualidade dos produtos e serviços, redução de custos, conscientização ambiental, eliminação de desperdícios, melhoria em atendimento e diagnósticos para os pacientes. O programa de controle da qualidade em mamografia é um instrumento para o gerenciamento da qualidade dos serviços que são oferecidos à população. A radiografia computadorizada (CR) em mamografia surge como uma importante ferramenta nas ações sistematizadas de controle do câncer de mama, na detecção precoce através de programas de rastreamento de segmentos populacionais, com exames periódicos. Para que se tenham mamografias de qualidade ótima na detecção do câncer de mama é necessário seguir critérios de qualidade da imagem e desempenho dos equipamentos. Os sistemas de radiografia computadorizada (CR) constituem um método eficiente e econômico de captura e conversão de radiografia em formato digital. Desde que as soluções digitais em mamografia vêm sendo utilizadas comercialmente, mostrou-se evidente que os sistemas de avaliação dos métodos analógicos não são apropriados para as tecnologias digitais. Por se tratar de um sistema novo no processo de aquisição de imagens médicas, ainda não se tem um método definido de avaliação estabelecido pelos órgãos reguladores nacionais. Os ensaios foram realizados no Laboratório de Calibração e Dosimetria do Centro de Desenvolvimento da Tecnologia Nuclear onde foi possível avaliar a cadeia da formação da imagem e parâmetros de qualidade da imagem como: contraste, resolução espacial, ruído, densidade ótica, razão sinal ruído, razão sinal contraste, distorção, artefatos e processamento. Esses parâmetros influenciam na capacidade de interpretação e visualização da imagem radiográfica, sendo estes determinantes para a tomada de decisão do diagnostico final. O propósito deste trabalho é o de analise de parâmetros e controle da qualidade de sistemas de radiologia computadorizada para mamografia a fim de apresentar indicadores que refletem a exposição à radiação em um detetor de imagem. O resultado final dos testes de caracterização do sistema digital avaliado foi satisfatório em todos os aspectos relativos à metodologia aplicada para avaliação dos testes, comprovando assim os benefícios dos sistemas digitais de aquisição de imagens médicas. O trabalho sugere um modelo de metodologia para avaliação do sistema de radiografia computadorizada em mamografia. / The development and the consolidation of new technologies in radiology became a permanent strategy of companies since they contribute to the increase of productivity, the upgrade of the quality of products and services, reduction of costs, environmental consciousness, elimination of waste and improvement of the diagnosis. The quality control program for mammography is an instrument for the management of the quality of services provided to the population. The Computed Radiography (CR) in mammography appears to be an important tool in the systematic actions for controlling the breast cancer; it also has an important role in the early detection through screening programs of population segments by periodic exams. Good mammography images are achieved if the criteria for image quality and equipment performance are complied with standards. The Computed Radiography systems are an efficient and economical method of capture and conversion of the diagnostic image to digital format. Since digital solutions in mammography have been used, it became evident that evaluation systems of analogical methods are not adequate to digital technologies. The CR is a new system for the acquisition process of medical images; therefore there are not yet standards with an established quality control evaluation method provided by national regulatory authority. Measurements were carried out in a CR of the Dosimetry and Calibration Laboratory of the Development Center of Nuclear Technology; it was possible to evaluate the image formation chain and image quality parameters as contrast, spatial resolution, noise, optical density, signal-noise ratio, signal-contrast ratio, distortion, test objects and processing method. The visualization and interpretation ability of the radiographic image are highly influenced by those parameters; they are determinant for taking decision of the final diagnostic. The purpose of this work was to analyze the image parameters and the quality control procedure of CR systems for mammography; indicators that reflect the radiation exposure in an image detector were recommended. The final result of the characterization tests in this digital system was statistically significant relative to all aspects to the applied methodology for tests evaluation, proving the benefits of this digital system for acquisition of medical images. This work suggests a methodology model for evaluating the computed radiography systems used for mammography purposes.