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Papers by nestor fabian virgen parra
Revista Colombiana de Médicina Física y Rehabilitación, 2014
Conflicto de interés: Ninguno La escala de goodenough-Harris y su utilidad en la detección de dis... more Conflicto de interés: Ninguno La escala de goodenough-Harris y su utilidad en la detección de discapacidad cognitiva en una población de niños de 3 a 13 años Goodenough-Harris scale and its usefulness in the detection of cognitive alteration children in the between 3 and 13 years old
Ratio Juris, 2013
La real justificación para un crecimiento continuo es permitir que cada ser humano cumpla con el ... more La real justificación para un crecimiento continuo es permitir que cada ser humano cumpla con el más precioso e íntimo objetivo de la vida: mejorar su autoestima como miembro de una sociedad que funcione bien. Por lo que el pensamiento sobre el desarrollo versa realmente sobre la economía de la dignidad.
Oncotarget, 2016
Standard clinicopathological variables are inadequate for optimal management of prostate cancer p... more Standard clinicopathological variables are inadequate for optimal management of prostate cancer patients. While genomic classifiers have improved patient risk classification, the multifocality and heterogeneity of prostate cancer can confound pre-treatment assessment. The objective was to investigate the association of multiparametric (mp)MRI quantitative features with prostate cancer risk gene expression profiles in mpMRI-guided biopsies tissues. Global gene expression profiles were generated from 17 mpMRI-directed diagnostic prostate biopsies using an Affimetrix platform. Spatially distinct imaging areas ('habitats') were identified on MRI/3D-Ultrasound fusion. Radiomic features were extracted from biopsy regions and normal appearing tissues. We correlated 49 radiomic features with three clinically available gene signatures associated with adverse outcome. The signatures contain genes that are over-expressed in aggressive prostate cancers and genes that are under-expressed in aggressive prostate cancers. There were significant correlations between these genes and quantitative imaging features, indicating the presence of prostate cancer prognostic signal in the radiomic features. Strong associations were also found between the radiomic features and significantly expressed genes. Gene ontology analysis identified specific radiomic features associated with immune/inflammatory response, metabolism, cell and biological adhesion. To our knowledge, this is the first study to correlate radiogenomic parameters with prostate cancer in men with MRI-guided biopsy.
Medical Imaging 2007: Image Processing, 2007
Accurate registration of diagnosis and treatment images is a critical factor for the success of r... more Accurate registration of diagnosis and treatment images is a critical factor for the success of radiotherapy. This study presents a feature-based image registration algorithm that uses a branch- and-bound method to search the space of possible transformations, as well as a Hausdorff distance metric to evaluate their quality. This distance is computed in the space of responses to a circular Gabor filter, in which, for each point of interest in both reference and subject images, a vector of complex responses to different Gabor kernels is computed. Each kernel is generated using different frequencies and variances of the Gabor function, which determines correspondent regions in the images to be registered, by virtue of its rotation invariance characteristics. Responses to circular Gabor filters have also been reported in literature as a successful tool for image classification; and in this particular application we utilize them for patient positioning in cranial radiotherapy. For test purposes, we use 2D portal images acquired with an electronic portal imaging device (EPID). Our method presents EPID-EPID registrations errors under 0.2 mm for translations and 0.05 deg for rotations (subpixel accuracy). We are using fiducial marker registration as the ground truth for comparisons. Registration times average 2.70 seconds based on 1400 feature points using a 1.4 GHz processor.
Reflexión Política, 2010
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
Revista Colombiana de Médicina Física y Rehabilitación, 2014
Conflicto de interés: Ninguno La escala de goodenough-Harris y su utilidad en la detección de dis... more Conflicto de interés: Ninguno La escala de goodenough-Harris y su utilidad en la detección de discapacidad cognitiva en una población de niños de 3 a 13 años Goodenough-Harris scale and its usefulness in the detection of cognitive alteration children in the between 3 and 13 years old
Ratio Juris, 2013
La real justificación para un crecimiento continuo es permitir que cada ser humano cumpla con el ... more La real justificación para un crecimiento continuo es permitir que cada ser humano cumpla con el más precioso e íntimo objetivo de la vida: mejorar su autoestima como miembro de una sociedad que funcione bien. Por lo que el pensamiento sobre el desarrollo versa realmente sobre la economía de la dignidad.
Oncotarget, 2016
Standard clinicopathological variables are inadequate for optimal management of prostate cancer p... more Standard clinicopathological variables are inadequate for optimal management of prostate cancer patients. While genomic classifiers have improved patient risk classification, the multifocality and heterogeneity of prostate cancer can confound pre-treatment assessment. The objective was to investigate the association of multiparametric (mp)MRI quantitative features with prostate cancer risk gene expression profiles in mpMRI-guided biopsies tissues. Global gene expression profiles were generated from 17 mpMRI-directed diagnostic prostate biopsies using an Affimetrix platform. Spatially distinct imaging areas ('habitats') were identified on MRI/3D-Ultrasound fusion. Radiomic features were extracted from biopsy regions and normal appearing tissues. We correlated 49 radiomic features with three clinically available gene signatures associated with adverse outcome. The signatures contain genes that are over-expressed in aggressive prostate cancers and genes that are under-expressed in aggressive prostate cancers. There were significant correlations between these genes and quantitative imaging features, indicating the presence of prostate cancer prognostic signal in the radiomic features. Strong associations were also found between the radiomic features and significantly expressed genes. Gene ontology analysis identified specific radiomic features associated with immune/inflammatory response, metabolism, cell and biological adhesion. To our knowledge, this is the first study to correlate radiogenomic parameters with prostate cancer in men with MRI-guided biopsy.
Medical Imaging 2007: Image Processing, 2007
Accurate registration of diagnosis and treatment images is a critical factor for the success of r... more Accurate registration of diagnosis and treatment images is a critical factor for the success of radiotherapy. This study presents a feature-based image registration algorithm that uses a branch- and-bound method to search the space of possible transformations, as well as a Hausdorff distance metric to evaluate their quality. This distance is computed in the space of responses to a circular Gabor filter, in which, for each point of interest in both reference and subject images, a vector of complex responses to different Gabor kernels is computed. Each kernel is generated using different frequencies and variances of the Gabor function, which determines correspondent regions in the images to be registered, by virtue of its rotation invariance characteristics. Responses to circular Gabor filters have also been reported in literature as a successful tool for image classification; and in this particular application we utilize them for patient positioning in cranial radiotherapy. For test purposes, we use 2D portal images acquired with an electronic portal imaging device (EPID). Our method presents EPID-EPID registrations errors under 0.2 mm for translations and 0.05 deg for rotations (subpixel accuracy). We are using fiducial marker registration as the ground truth for comparisons. Registration times average 2.70 seconds based on 1400 feature points using a 1.4 GHz processor.
Reflexión Política, 2010
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto