Browsing by Author "Chabert, Steren"

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    Benchmarking YOLO Models for Intracranial Hemorrhage Detection Using Varied CT Data Sources
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2024) Tapia, Gonzalo; Allende-Cid, Hector; Chabert, Steren; Mery Quiroz Domingo Arturo; Salas, Rodrigo
    Intracranial hemorrhages (ICH) are a significant challenge in emergency medicine due to the critical nature of a timely and accurate diagnosis. This study evaluates the performance of six versions of the You Only Look Once (YOLO) object detection model, from YOLOv5 to YOLOv10, in detecting ICH using computed tomography (CT) scans. The primary focus is understanding the advancements in YOLO architectures over time and their impact on detection accuracy and inference speed. The study used the Brain Hemorrhage Extended Dataset (BHX), comprising 491 CT scans with annotations for six types of hemorrhages: epidural, subdural, subarachnoid, intraparenchymal, intraventricular, and chronic hemorrhage, and introduces a new data set obtained from a major hospital in Chile. The models were trained using a combination of single-class and multi-class approaches to address class imbalance and were evaluated based on precision, recall, F1 score, and mean average precision (mAP). The models were evaluated in three distinct contexts: 1) a biased scenario where images of the same individual could appear in both training and testing sets, 2) a cross-validation setup ensuring the independence of images by separating the sets based on subjects, and 3) an external validation using one dataset for training and the Chilean dataset for testing, maintaining full independence between training and evaluation. The findings indicate that YOLOv8 and YOLOv10 demonstrate superior detection accuracy and inference efficiency performance, respectively, compared to previous versions. In particular, with image independence, YOLOv8 reached the highest average mAP for all classes, with a score of 0.4. This comparative analysis provides information on the effectiveness of architectural advances in YOLO models for medical applications and suggests directions for future improvements in ICH detection.
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    Development of mechanical ventilators in Chile. Chronicle of the initiative "Un Respiro para Chile
    (2022) Bugedo, Guillermo; Tobar, Eduardo; Alegria, Leyla; Oviedo, Vanessa; Arellano, Daniel; Basoalto, Roque; Enberg, Luis; Suarez, Pablo; Bitran, Eduardo; Chabert, Steren; Bruhn, Alejandro
    At the beginning of the COVID-19 pandemic in Chile, in March 2020, a projection indicated that a significant group of patients with pneumonia would require admission to an Intensive Care Unit and connection to a mechanical ventilator. Therefore, a paucity of these devices and other supplies was predicted. The initiative "Un respiro para Chile" brought together many people and institutions, public and private. In the course of three months, it allowed the design and building of several ventilatory assistance devices, which could be used in critically ill patients.
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    Quantitative description of the morphology and ossification center in the axial skeleton of 20-week gestation formalin-fixed human fetuses using magnetic resonance images
    (WILEY, 2012) Chabert, Steren; Villalobos, Manuel; Ulloa, Patricia; Salas, Rodrigo; Tejos, Cristian; San Martin, Sebastian; Pereda, Jaime
    Objectives Human tissues are usually studied using a series of two-dimensional visualizations of in vivo or cutout specimens. However, there is no precise anatomical description of some of the processes of human fetal development. The purpose of our study is to develop a quantitative description of the normal axial skeleton by means of high-resolution three-dimensional magnetic resonance (MR) images, collected from six normal 20-week-old human fetuses fixed in formaldehyde.