Examinando por Autor "Hoyos, Diego"
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Ítem Automatic segmentation of a cerebral glioblastoma using a smart computational technique(Sociedad Venezolana de Farmacología Clínica y Terapéutica, 2018) Vera, Miguel; Huérfano, Yoleidy; Valbuena, Oscar; Hoyos, Diego; Arias, Yeni; Contreras, Yudith; Salazar, Williams; Vera, María Isabel; Borrero, Maryury; Vivas, Marisela; Hernández, Carlos; Barrera, Doris; Molina, Ángel Valentín; Martínez, Luis Javier; Salazar, Juan; Gelvez, ElkinWe propose an intelligent computational technique for the image segmentation of a type IV brain tumor, identified as multiform glioblastoma (MGB), which is present in multi-layer computed tomography images. This technique consists of 3 stages developed in the three-dimensional domain. They are: pre-processing, segmentation and validation. During the validation stage, the Dice coefficient (Dc) is considered in order to compare the segmentations of the MGB, obtained automatically, with the segmentations of the MGB generated manually, by a neuro-oncologist. The combination of parameters linked to the highest Dc, allows to establish the optimal parameters of each of the computational algorithms that make up the proposed nonlinear technique. The obtained results allow to report a Dc higher than 0.88, validating a good correlation between the manual segmentations and those produced by the computational technique developed.Ítem High grade glioma segmentation in magnetic resonance imaging(Sociedad Latinoamericana de Hipertensión, 2018) Vera, Miguel; Huérfano, Yoleidy; Martínez, Luis Javier; Contreras, Yudith; Salazar, Williams; Vera, María Isabel; Valbuena, Oscar; Borrero, Maryury; Hernández, Carlos; Barrera, Doris; Molina, Ángel Valentín; Salazar, Juan; Gelvez, Elkin; Sáenz, Frank; Hoyos, Diego; Arias, YenyThrough this work we propose a computational technique for the segmentation of magnetic resonance images (MRI) of a brain tumor, identified as high grade glioma (HGG), specifically grade III anaplastic astrocytoma. This technique consists of 3 stages developed in the threedimensional domain. They are: pre-processing, segmentation and post-processing. The pre-processing stage uses a thresholding technique, morphological erosion filter (MEF), in gray scale, followed by a median filter and a gradient magnitude algorithm. On the other hand, in order to obtain a HGG preliminary segmentation, during the segmentation stage a clustering algorithm called region growing (RG) is implemented and it is applied to the preprocessed images. The RG requires, for its initialization, a seed voxel whose coordinates are obtained, automatically, through the training and validation of an intelligent operator based on support vector machines (SVM). Due to the high sensitivity of the RG to the location of the seed, the SVM is implemented as a highly selective binary classifier. During the post-processing stage, a morphological dilation filter is applied to preliminary segmentation generated by RG. The percent relative error (PrE) is considered by comparing the segmentations of the HGG, generated manually by a neuro-oncologist, with the dilated segmentations of the HGG, obtained automatically. The combination of parameters linked to the lowest PrE, allows establishing the optimal parameters of each computational algorithms that make up the proposed computational technique. The obtained results allow reporting a PrE of 11.10%, which indicates a good correlation between the manual segmentations and those produced by the computational technique developed.