ABSTRACT
BACKGROUND: Sudden cardiac death (SCD) can be the first clinical event of Chagas heart disease (CHD). However, current guidelines contain no clear recommendation for early cardioverter-defibrillator implantation. Using imaging modalities, we evaluated associations among autonomic denervation, myocardial hypoperfusion, fibrosis and ventricular arrhythmia in CHD. METHODS AND RESULTS: Twenty-nine patients with CHD and preserved left ventricular function underwent 123I-metaiodobenzylguanidine (MIBG) scintigraphy, 99mTc-methoxyisobutylisonitrile (MIBI) myocardial perfusion and cardiac magnetic resonance imaging (MRI). They were divided into arrhythmic (≥ 6 ventricular premature complexes/h and/or non-sustained ventricular tachycardia on 24-hour Holter, n = 15) and non-arrhythmic (< 6 ventricular premature complexes/h and no ventricular tachycardia; n = 14) groups. The arrhythmic group had higher denervation scores from MIBG imaging (23.2 ± 18.7 vs 5.6 ± 4.9; P < .01), hypoperfusion scores from MIBI SPECT (4.7 ± 6.8 vs 0.29 ± 0.6: P = .02), innervation/perfusion mismatch scores (18.5 ± 17.5 vs 5.4 ± 4.8; P = .01) and fibrosis by late gadolinium enhancement on MRI (14.3% ± 13.5% vs 4.0% ± 2.9%; P = .04) than the non-arrhythmic group. CONCLUSION: These imaging parameters were associated with ventricular arrhythmia in early CHD and may enable risk stratification and the implementation of primary preventive strategies for SCD.
Subject(s)
Chagas Cardiomyopathy , Chagas Disease , Coronary Artery Disease , Myocardial Ischemia , Ventricular Premature Complexes , Humans , Chagas Cardiomyopathy/complications , Chagas Cardiomyopathy/diagnostic imaging , 3-Iodobenzylguanidine , Contrast Media , Gadolinium , Death, Sudden, Cardiac/prevention & control , Fibrosis , Chagas Disease/complications , Chagas Disease/diagnostic imaging , Autonomic DenervationABSTRACT
BACKGROUND: Soft tissue attenuation artifacts are the most common cause of misinterpretation in myocardial perfusion Imaging (MPI). Few studies assessing the value of prone imaging in women have been published. Breast attenuation artifacts can be present in up to 40% of the MPI studies in women. OBJECTIVES: This study aimed at evaluating the potential impact of prone MPI on breast attenuation, with a critical analysis of activity optimization and breast size influence. METHODS: MPI of an Anthropomorphic Torso Phantom with silicone breast prostheses and equivalent adipose tissue was compared to a standard MPI database. RESULTS: A medical qualitative and semiquantitative analysis demonstrated higher uptake in the LV anterior segments in the prone position for all injected activities. An artificial myocardium lesion was diagnosable in the right segment in all images, which shows that prone positioning would not mask a true lesion and it assists the cardiologist with a more accurate analysis. These results showed that it is possible to optimize the activity to be injected by up to 55.6% when using combined supine-prone images. CONCLUSION: Prone position has a high impact on the interpretation of MPI in female patients since it reduces the breast attenuation artifacts, and optimizes the radiation protection of the patient and all staff involved in the procedure, making it more cost-effective.
Subject(s)
Breast/diagnostic imaging , Myocardial Perfusion Imaging , Artifacts , Female , Humans , Phantoms, Imaging , Prone PositionABSTRACT
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. .
ABSTRACT
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 (99m)Tc-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.
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.
