Examinando por Autor "Madriz, Delia"
Mostrando 1 - 5 de 5
Resultados por página
Opciones de ordenación
Ítem Automatic centerline extraction of left coronary artery from X–ray rotational angiographic images(International Society For Optical Engineering, 2018) Chacón, Gerardo; Rodríguez, Johel; Bermúdez, Valmore; Vera, Miguel; Madriz, Delia; Bravo, AntonioRotational X-ray coronary angiography is a medical imaging technique safe and effective in identifying of the luminal disease, which considers a significant reduction in radiation exposure and contrast medium volume compared to conventional angiography. The main objective of this research is to propose a computational approach to automatically extract a description of the morphopatological shape of the left coronary artery by means the centerlines of this vessel. The proposal is based on a sequential design which involves image enhancement, identification of all the types of vascular points belonging to the vascular system, construction of the coronary tree and tracking of the centerlines along the rotational angiography sequence. Some results obtained after applying this method to monoplane rotational X–ray image sequences are presented.Ítem Computational assessment of stomach tumor volume from multi-slice computerized tomography images in presence of type 2 cancer [version 2; referees: 1 approved, 1 not approved](F1000 Research Ltda., 2018-07) Chacón, Gerardo; Rodríguez, Johel E.; Bermúdez, Valmore; Vera, Miguel; Hernández, Juan Diego; Vargas, Sandra; Pardo, Aldo; Lameda, Carlos; Madriz, Delia; Bravo, Antonio J.Background: The multi–slice computerized tomography (MSCT) is a medical imaging modality that has been used to determine the size and location of the stomach cancer. Additionally, MSCT is considered the best modality for the staging of gastric cancer. One way to assess the type 2 cancer of stomach is by detecting the pathological structure with an image segmentation approach. The tumor segmentation of MSCT gastric cancer images enables the diagnosis of the disease condition, for a given patient, without using an invasive method as surgical intervention. Methods: This approach consists of three stages. The initial stage, an image enhancement, consists of a method for correcting non homogeneities present in the background of MSCT images. Then, a segmentation stage using a clustering method allows to obtain the adenocarcinoma morphology. In the third stage, the pathology region is reconstructed and then visualized with a three–dimensional (3–D) computer graphics procedure based on marching cubes algorithm. In order to validate the segmentations, the Dice score is used as a metric function useful for comparing the segmentations obtained using the proposed method with respect to ground truth volumes traced by a clinician. Results: A total of 8 datasets available for patients diagnosed, from the cancer data collection of the project, Cancer Genome Atlas Stomach Adenocarcinoma (TCGASTAD) is considered in this research. The volume of the type 2 stomach tumor is estimated from the 3–D shape computationally segmented from the each dataset. These 3–D shapes are computationally reconstructed and then used to assess the morphopathology macroscopic features of this cancer. Conclusions: The segmentations obtained are useful for assessing qualitatively and quantitatively the stomach type 2 cancer. In addition, this type of segmentation allows the development of computational models that allow the planning of virtual surgical processes related to type 2 cancer.Ítem Reconstrucción 3-D del Ventrículo Izquierdo de Corazón Humano a partir de Angiocardiografía Rotacional por Rayos X Usando Conectores Difusos(Latin American and Caribbean Consortium of Engineering Institutions, LACCEI, 2019-07) Gerardo Chacón, José; Rodríguez, Johel; Vera, Miguel; Madriz, Delia; Bravo, AntonioEn este trabajo, se propone un método de reconstrucción tri-dimensional aproximada del ventrículo izquierdo de corazón humano. El método realiza la reconstrucción a partir de la información asociada a los niveles de gris y considera la geometría de proyección perspectiva expresada por el modelo pin-hole. El método está inspirado en la etapa de aproximación utilizada por los enfoques difuso y probatorio. La reconstrucción tridimensional se realiza combinando la retroproyección de cada una de las proyecciones de la cavidad en la misma fase del ciclo cardíaco. La información de nivel de gris de las imágenes de entrada se combina mediante conectores difusos. Los conectores difusos considerados corresponden a norma T, conorma T, función de promediación y el operador de compensación generalizada del conector difusa lógico. El método de reconstrucción genera errores menores al 13.23%.Ítem Resonancia magnética en cardiología(Cooperativa servicios y suministros 212518 RS, 2017) Bravo, Antonio J.; Vera, Miguel; Madriz, Delia; Contreras-Velásquez, Julio; Vera, María; Chacón, José; Wilches-Durán, Sandra; Graterol-Rivas, Modesto; Riaño-Wilches, Daniela; Rojas, Joselyn; Bermúdez, ValmoreEl principio de la resonancia magnética nuclear basado en la utilización de ondas de radio frecuencia y campos magnéticos es el fundamento del proceso de generación de imágenes tridimensionales por resonancia magnética. Los avances alcanzados en esta modalidad imagenológica han permitido su aplicación para la obtención de información tanto morfológica como funcional del sistema cardiovascular. En el presente artículo, se hace una revisión de tales avances y de sus principales aplicaciones en cardiología.Ítem A score function as quality measure for cardiac image enhancement techniques assessment(Sociedad Latinoamericana de Hipertensión, 2019) Chacón, Gerardo; Rodríguez, Johel E.; Bermúdez, Valmore; Flórez, Anderson; Del Mar, Atilio; Pardo, Aldo; Lameda, Carlos; Madriz, Delia; Bravo, Antonio J.A score function useful as a quantitative measure of the performance of the medical image enhancement techniques is reported in this paper. The measure proposed is based on merging of full–reference and blind–reference image enhancement measures. The score function is the average of the weighted sum of the image enhancement measures normalized between zero and one. The novel measure is validated considering as a hypothesis that values maximizing score function have that maximize the values of the metrics (Dice coefficient) used to evaluate certain previously reported cardiac image segmentation approach. The values of score function and Dice score reached the maximum value for the same cardiac volumes segmented.