ABSTRACT
OBJETIVO: Criar um atlas de cintilografia de perfusão miocárdica e verificar sua aplicabilidade no auxílio computadorizado à detecção de defeitos perfusionais miocárdicos em pacientes portadores de cardiopatia isquêmica. MATERIAIS E MÉTODOS: O atlas foi criado com imagens de cintilografia de perfusão miocárdica, em condições de repouso e estresse, de 20 pacientes de ambos os gêneros com baixa probabilidade de doença arterial coronariana e julgadas normais por dois observadores experientes. Técnicas de registro de imagens e operações matemáticas sobre imagens foram utilizadas para obtenção de modelos de média e desvio-padrão da captação miocárdica percentual de cada gênero e condição fisiológica. RESULTADOS: Imagens de um paciente masculino e um feminino foram alinhadas com os atlas correspondentes, e os voxels apresentando valores de captação percentual dois desvios-padrão abaixo da média da respectiva região do atlas foram destacados nos cortes tomográficos e confirmados como defeitos de perfusão por dois observadores experientes. CONCLUSÃO: Demonstramos a criação de um atlas de cintilografia de perfusão miocárdica e obtivemos resultados promissores na sua utilização para auxílio à detecção de defeitos perfusionais. Entretanto, uma validação prospectiva com um número mais representativo de casos é necessária.
OBJECTIVE: To develop an atlas of myocardial perfusion scintigraphy and evaluating its applicability in computer-aided detection of myocardial perfusion defects in patients with ischemic heart disease. MATERIALS AND METHODS: The atlas was created with rest-stress myocardial perfusion scintigraphic images of 20 patients of both genders with low probability of coronary artery disease and considered as normal by two experienced observers. Techniques of image registration and mathematical operations on images were utilized for obtaining template images depicting mean myocardial uptake and standard deviation for each gender and physiological condition. RESULTS: Myocardial perfusion scintigraphy images of one male and one female patient were aligned with the corresponding atlas template image, and voxels with myocardial uptake rates two standard deviations below the mean voxel value of the respective region in the atlas template image were highlighted on the tomographic sections and confirmed as perfusion defects by both observers. CONCLUSION: The present study demonstrated the creation of an atlas of myocardial perfusion scintigraphy with promising results of this tool as an aid in the detection of myocardial perfusion defects. However, further prospective validation with a more representative sample is recommended.
Subject(s)
Humans , Heart/physiopathology , Diagnosis, Computer-Assisted , Image Processing, Computer-Assisted , Myocardium , Nuclear Medicine , Radionuclide Imaging , Reference Books , Radionuclide Imaging/standards , Tomography, Emission-Computed, Single-PhotonABSTRACT
El presente artículo realiza una descripción físico-matemática de los principales factores físicos que caracterizan la calidad de la imagen en Medicina Nuclear, así como una descripción conceptual de la degradación que sufre la información proveniente del objeto debido al sistema de imagen (cámara gamma). Seguidamente se realiza una presentación crítica de algunos métodos cualitativos y cuantitativos de valoración de la calidad de la imagen, colaterales al tradicional control de calidad del equipamiento, como son el análisis ROC, las Técnicas de Clustering y el Análisis Discriminante. Dentro de estas dos últimas, se analizan los principales factores que determinan la calidad de la imagen y cómo los mismos se traducen en cambios en los valores cuantitativos de las principales variables físicas que la caracterizan. Se realiza además una comparación entre los métodos, resaltando su utilidad para monitorear calidad de imagen, así como sus principales ventajas y desventajas.
Subject(s)
Humans , Discriminant Analysis , Cluster Analysis , Radionuclide Imaging/standards , Quality Control , ROC Curve , Nuclear Medicine , Tomography, Emission-Computed, Single-Photon , Gamma Cameras/standards , Diagnostic Imaging/standards , Physics , Mathematics , Contrast SensitivitySubject(s)
Humans , Female , Sentinel Lymph Node Biopsy/standards , Radionuclide Imaging/standards , Lymphatic Metastasis , Lymphatic Metastasis/pathology , Breast Neoplasms/complications , Lymph Nodes , Lymph Nodes/pathology , Axilla , Carcinoma, Ductal, Breast/complications , Neoplasm Staging/methods , Neoplasm Invasiveness , Neoplasm Invasiveness/pathology , Radiopharmaceuticals , False Negative ReactionsABSTRACT
A method for optimizing the administered activity in Static Nuclear Medicine Studies is validated by comparison with ROC curve. Discriminant analysis of image quality is the applied statistical technique. The constructed linear function owns as dependent parameters, the differentiated levels of image quality obtained by observer's criterion. The percentage of cases correctly classified is analyzed. The minimum value of the administered activity, which permit good image quality, can be proposed from the best results of the parameters selected by the function. The method was tested using planar images from a Jaszczak phantom, acquired under four activities (1088 MBq, 962 MBq, 740 MBq and 562 MBq). Two of the six measured Background-to-Signal ratios (S/B) were the parameters able to construct the function with high correlation respect to the expert criterion. The value of 740 MBq was the optimum after method application. The results were coincident with the application of ROC-analysis.