Repositorio :: Examinando por Autor "Bravo, Antonio"

Examinando por Autor "Bravo, Antonio"

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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, Antonio
Rotational 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.
A computational approach for Leishmania genus protozoa detection in bone marrow samples from patients with visceral Leishmaniasis
(Saber UCV, Universidad Central de Venezuela, 2020) Isaza-Jaimes, Angélica; Bérmudez, Valmore; Bravo, Antonio; Sierra Castrillo, Jhoalmis; Hernández Lalinde, Juan Diego; Fossi, Cleiver A.; Flórez, Anderson; Rodríguez, Johel E.
This article reports a three-stage computational approach for the automatic detection of Leishmania protozoan in light microphotograph from bone marrow samples extracted from patients with visceral Leishmaniasis. The first stage corresponds to the pre-processing of the microscopy images, in which initially a low-pass filter or softener was applied to attenuate the undesired information associated with the images and preserve the edges in the objects contained in the images. The pre-processing stage concluded with the applica tion of consistent gradient operators to the smoothed images to emphasise the changes of the intensities associated with the protozoa edges by determining the gradient module. In the second stage, a procedure-oriented to the selection of regions of interest that were candidates to contain parasites in the pre-processed images was developed, based on the intensity analysis associated with a set of intensity profiles selected from the smoothed images. In the final stage, each region of interest containing protozoa was analysed on the gradient module by a technique based on polar maps, to clas sify its content as a parasite of the genus Leishmania or not. The application of the proposed computational approach to a set of samples of patients with Visceral Leishmaniasis generated a recognition parasite percentage of approximately 80%
A computational methodology for the staging of lung tumors considering geometric descriptors
(Sociedad Venezolana de Farmacología Clínica y Terapéutica, 2020) Vera, Miguel; Huérfano, Yoleidy; Bravo, Antonio
Lung diseases diagnosis, specifically the presence of lung tumors, is usually performed with the support of radiological techniques. Computed tomography is the most widely used imaging technique to confirm the presence of this disease. When several researchers require identifying the morphology of these tumors, they deal problems related to the poor delimitation of the borders associated with the anatomical structures that compound the lung, Poisson noise, the streak artifact and the non-homogeneity of gray levels that define each object in the chest images. In this paper, a methodology has been presented to identify in which stage (staging) the mentioned tumors are. For this, first, anisotropic diffusion filter and magnitude of the gradient filter are used in order to address the aforementioned problems. Second, a smart operator and the level set lgorithm are used to segment lung tumors. Finally, considering these segmentations, a set of geometric descriptors is obtained, and it allows staging of such tumors to be precisely established, generating results that are in high correspondence with the reference data, linked to the analyzed tagged images.
Description and use of Three-Dimensional Numerical Phantoms of Cardiac Computed Tomography Images
(MDPI, 2022) Vera, Miguel; Bravo, Antonio
The World Health Organization indicates the top cause of death is heart disease. These diseases can be detected using several imaging modalities, especially cardiac computed tomography (CT), whose images have imperfections associated with noise and certain artifacts. To minimize the impact of these imperfections on the quality of the CT images, several researchers have developed digital image processing techniques (DPIT) by which the quality is evaluated considering several metrics and databases (DB), both real and simulated. This article describes the processes that made it possible to generate and utilize six three-dimensional synthetic cardiac DBs or voxels-based numerical phantoms. An exhaustive analysis of the most relevant features of images of the left ventricle, belonging to a real CT DB of the human heart, was performed. These features are recreated in the synthetic DBs, generating a reference phantom or ground truth free of imperfections (DB1) and five phantoms, in which Poisson noise (DB2), stair-step artifact (DB3), streak artifact (DB4), both artifacts (DB5) and all imperfections (DB6) are incorporated. These DBs can be used to determine the performance of DPIT, aimed at decreasing the effect of these imperfections on the quality of cardiac images.
Ecocardiografía aumentada basada en una estrategia computacional híbrida
(Saber UCV, Universidad Central de Venezuela, 2021) Vera, Miguel; Bravo, Antonio; Del Mar, Atilio; Vera, María; Huérfano, Yoleidy
El ultrasonido (US) es el principio físico básico que, en el contexto imagenológico médico, permite la generación de imágenes ecográficas de diversas estructuras del cuerpo humano. Usualmente, la ecocardiografía transtorácica bidimensional (ET2) es una técnica disponible en la mayoría de centros de atención médica y puede generar, de manera no invasiva y económica, imágenes de casi todas las regiones del corazón. No obstante, la información contenida en estas representaciones gráficas se ve afectada por imperfecciones que afectan su calidad, entre las cuales destaca el ruido ultrasónico moteado. Tales imperfecciones, por una parte, constituyen un verdadero desafío para quienes deben analizar las imágenes ET2 y, por la otra, abre la posibilidad para la búsqueda de alternativas tendientes a elevar la calidad de la información obtenida en la ecografía recurriendo a variantes de modalidades de US, así como al uso de otras técnicas imagenológicas más complejas ó técnicas de procesamiento digital de imágenes (PDI). En el presente artículo se considera la aplicación de una PDI híbrida basada en similaridad y transformada de copa de sombrero blanco que acondiciona, adecuadamente, imágenes de ET2 posibilitando una mejor visualización de las estructuras anatómicas presentes en ellas. Este hecho puede contribuir, preliminarmente, en dos direcciones: a) Reducir la necesidad de considerar variantes de US como, por ejemplo, el US de contraste o emplear otras modalidades de imagen que si bien es cierto mejoran la apariencia de las imágenes, constituyen opciones más costosas que afectan los recursos económicos de los pacientes y de los centros de salud. b) Proporcionar a los cardiólogos imágenes de mejor aspecto cualitativo que les permitan obtener descriptores útiles en el diagnóstico de diversas enfermedades del corazón.
Liver abscess mimicking tumor: A pediatric case report
(Sociedad Venezolana de Farmacología y de Farmacología Clínica y Terapéutica, 2020) Vera, María; Vera, Miguel; Bravo, Antonio
A case report of a 3-year-old boy with past medical history of intestinal partially treated amebiasis, is presented. The patient was admitted to Pediatric Unit, San Cristóbal Central Hospi- tal, Táchira, Venezuela, with abdominal pain and fever. An abdominal bloating and a 3 cm palpable hepatomegaly below the right costal margin were assessed. Abdominal ultrasound revealed a liver enlarged in the right antero-superior area. A rounded space-occupying lesion, predominantly solid, with mixed-echo patterns, was assessed using ultrasound. The preliminary diagnosis issued was of acute medical abdomen with hepatic space-occupying lesion considered amebic liver abscess or liver tumor, moderate hypochromic microcytic anemia, and malnutrition with short stature. During the case evolution, a frst computerized tomography exploration was necessary in order to exploit the capacity of this imaging tech- nique to scan an abscess as a peripheral pseudo-capsule showing rim enhancement. Nevertheless, this theoretical shape associated with abscesses on computerized tomog- raphy scans was unable to verify in this study. At this point, the mixed-echo patterns of the preliminary ultrasound study and the imprecision of the computerized tomography scan to categorize the lesion as an abscess or a tumor, do not allow establishing a defnitive diagnosis. A management based on antibiotic therapy is then proposed. The progression of the space-occupying lesion was performed using ultrasound and computerized tomography scans during the clinical evolution. The imaging controls probe a slight decrease of the liver le- sion, which is diagnosed as a liver abscess. Percutaneous transhepatic drainage was performed. An amoebic liver ab- scess in resolution was fnally diagnosed.
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, Antonio
En 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%.
Usefulness of calcium score and computed tomography images in patients with nonspecific chest pain: A case report
(Sociedad Venezolana de Hipertensión, 2020) Vera, Miguel; Bravo, Antonio; Del Mar, Atilio
Coronary calcium is a marker of the presence and extent of atherosclerosis, capable of providing prognostic information in addition to traditional risk factors. Additionally, the coronary calcium test has as an associated descriptor the calcium score or calcium score (Cs) which is useful, mainly, for the risk stratification of asymptomatic patients, whereas in patients with acute or chronic chest pain, it is required, usually, coronary axial computed tomography. In this article, we present the clinical case of a 59-year-old male patient with a history of chronic hypertension and mixed hyperlipidemia who consults for presenting non-specific chest discomfort, without irradiation, of 3 months of evolution, which has been progressively increasing and exacerbated with intense effort; while it improves with rest. No abnormalities suggestive of myocardial ischemia was observed on the 12-lead surface electrocardiogram. A quantification of the Cs is performed, which reports a total value of 350 Hounsfield units (HU) equivalent to acute coronary disease. Due to the high volume, mass and concentration of calcium in a single artery, located at 310 HU in the right descending coronary artery (ADA), together with the clinical and risk factors, it was decided to perform a cardiac catheterization with a finding of 90 % in the proximal segment of the ADA, followed by the respective coronary angioplasty and coronary stent implantation processes.
Una visión acerca de la Leishmaniasis americana y de su comportamiento epidemiológico
(Sociedad Venezolana de Farmacología Clínica y Terapéutica, 2018) Isaza-Jaimes, Angelica; Rodríguez, Johel E; Chacón, Gerardo; Bravo, Antonio; Silva Sarabia, Christian
La Leishmaniasis es una enfermedad causada por un parásito protozoario del género Leishmania. Es considerada una enfermedad autóctona de progresión lenta, y epidemiológicamente tratada en las Américas, como un trastorno parasitario transmitido por la picadura de un mosquito hematófago infectado del género Lutzomyia. Diversos estudios han concluido que las tasas reales de incidencia de Leishmaniasis son sustancialmente altas en todo el mundo y su prevalencia es alta en países de las Américas. En el presente artículo, se muestra el resultado de una revisión documental la cual se enfoca en realizar una descripción de las especies del protozoario del género Leishmania en las Américas, se caracteriza clínicamente la Leishmaniasis cutánea y visceral, y se muestra una clasificación taxonómica de Leishmania en el continente. Adicionalmente, se trata el ciclo de vida del parásito protozoario, los vectores, y algunos aspectos epidemiológicosn acerca de las formas clínicas que componen la Leishmanias. Se consideró el método de revisión documental, a través de la técnica de análisis de contenido para el desarrollo del presente trabajo.

Examinando por Autor "Bravo, Antonio"

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