ABSTRACT
Abstract Cardiovascular diseases are among the leading causes of mortality and morbidity in the world. In different cardiac diseases, the neuronal function of the heart is impaired. Nevertheless, the development of a simple method to assess the autonomic effects on the heart and/or autonomic dysfunction is a challenge. The evaluation of autonomic innervation in cardiac diseases has helped to improve the knowledge of the pathophysiology of these conditions, as well as to provide information on their prognosis. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are currently the only imaging methods that allow in vivo assessment of cardiac innervation. The majority of SPECT and PET radiotracers evaluate sympathetic neuronal integrity using presynaptic imaging agents that are either labeled as endogenous transmitters or analogues. Postsynaptic imaging agents have also been developed to study sympathetic neuronal integrity, as well as tracers to investigate the parasympathetic nervous system. These methods may be used to analyze the innervation of the heart and allow for early detection of abnormalities caused by, for example, ischemia, heart failure, cardiomyopathies, cardiotoxicity, and arrhythmogenic disorders. This review provides an overview of cardiac innervation evaluation and their application in the assessment of heart disease.
ABSTRACT
Objetivo: Realizar um estudo de otimização de exames de cintilografia de perfusão miocárdica. Materiais e Métodos: Foram adquiridas imagens de um objeto simulador antropomórfico de tórax contendo coração, pulmões, fígado e coluna vertebral, em uma gama câmara SPECT GE modelo Ventri, utilizando-se diferentes atividades e variando-se os tempos de aquisição, de forma a verificar a influência destes parâmetros na qualidade da imagem clínica reconstruída. Foi utilizado o radiofármaco 99mTc-sestamibi e os testes realizados foram avaliados clinicamente a partir de notas, tanto para o summed stress score quanto para a qualidade técnica da imagem e perfusão. As quantificações foram realizadas pelo software ImageJ. Resultados: Os resultados demonstraram que, para o tempo padrão utilizado na realização dos exames de 15 segundos por ângulo, a atividade injetada poderia ser reduzida em 33,34%. Além disso, se o tempo usual de exame for reduzido em 54,34% (7 segundos por ângulo), ainda assim a atividade padrão injetada poderia ser reduzida em 16,67%, sem prejudicar a qualidade da imagem e a confiabilidade do diagnóstico. Conclusão: O método desenvolvido e os resultados obtidos podem ser utilizados para o desenvolvimento de um estudo clínico de pacientes em um protocolo otimizado. .
Objective: To develop a study aiming at optimizing myocardial perfusion imaging. Materials and Methods: Imaging of an anthropomorphic thorax phantom with a GE SPECT Ventri gamma camera, with varied activities and acquisition times, in order to evaluate the influence of these parameters on the quality of the reconstructed medical images. The 99mTc-sestamibi radiotracer was utilized, and then the images were clinically evaluated on the basis of data such as summed stress score, and on the technical image quality and perfusion. The software ImageJ was utilized in the data quantification. Results: The results demonstrated that for the standard acquisition time utilized in the procedure (15 seconds per angle), the injected activity could be reduced by 33.34%. Additionally, even if the standard scan time is reduced by 53.34% (7 seconds per angle), the standard injected activity could still be reduced by 16.67%, without impairing the image quality and the diagnostic reliability. Conclusion: The described method and respective results provide a basis for the development of a clinical trial of patients in an optimized protocol. .