Search results for "aging."

K-nearest neighbor driving active contours to delineate biological tumor volumes

2019

Abstract An algorithm for tumor delineation in positron emission tomography (PET) is presented. Segmentation is achieved by a local active contour algorithm, integrated and optimized with the k-nearest neighbor (KNN) classification method, which takes advantage of the stratified k-fold cross-validation strategy. The proposed approach is evaluated considering the delineation of cancers located in different body districts (i.e. brain, head and neck, and lung), and considering different PET radioactive tracers. Data are pre-processed in order to be expressed in terms of standardized uptake value, the most widely used PET quantification index. The algorithm uses an initial, operator selected re…

Food tray sealing fault detection using hyperspectral imaging and PCANet

2020

Abstract Food trays are very common in shops and supermarkets. Fresh food packaged in trays must be correctly sealed to protect the internal atmosphere and avoid contamination or deterioration. Due to the speed of production, it is not possible to have human quality inspection. Thus, automatic fault detection is a must to reach high production volume. This work describes a deep neural network based on Principal Component Analysis Network (PCANet) for food tray sealing fault detection. The input data come from hyperspectral cameras, showing more characteristics than regular industrial cameras or the human eye as they capture the spectral properties for each pixel. The proposed classification…

Addressing the Occlusion Problem in Augmented Reality Environments with Phantom Hollow Objects

2018

Occlusion handling is essential to provide a seamless integration of virtual and real objects in AR applications. Different approaches have been presented with a variety of technologies, environment conditions and methods. Among these methods, 3D model-based occlusion approaches have been extensively used. However, these solutions could be too time-consuming in certain situations, since they must render all the occlusion objects even though they are invisible. For this reason, we propose an inverse 3D model-based solution for handling occlusions, designed for those AR applications in which virtual objects are placed inside a real object with holes or windows. With this restriction, the occl…

Abnormal Textures Identification Based on Digital Hilbert Optics Methods: Fundamental Transforms and Models

2017

The article presents the abnormal textures identification technology based on structural and statistical models of amplitude-phase images (APIm) – multidimensional data arrays (semantic models) and statistical correlation analysis methods using the generalized discrete Hilbert transforms (DHT) – 2D Hilbert (Foucault) isotropic (HTI), anisotropic (HTA) and total transforms – AP-analysis (APA) to calculate the APIm. The identified fragments of textures are obtained as examples of experimental observation of real mammograms contains areas of pathological tissues. The DHT based information technology as conceptual chart description is discussed and illustrated with DHO domain images. As additio…

Ecografía intestinal y abdomen agudo: más allá de la apendicitis aguda

2021

Resumen El abdomen agudo es un motivo de consulta habitual en los servicios de urgencias. Sus causas son multiples, y entre ellas se encuentran diversas enfermedades del tracto gastrointestinal. Si bien la tomografia computarizada es la tecnica mas aceptada, con frecuencia se lleva a cabo una ecografia abdominal inicialmente, mediante la cual es posible establecer la sospecha de patologia intestinal. Este articulo describe las caracteristicas ecograficas de diversos trastornos intestinales que cursan con abdomen agudo, como la diverticulitis aguda, la obstruccion intestinal, la perforacion gastrointestinal, la isquemia intestinal, la necrosis aguda de la grasa intraabdominal y una miscelane…

Paraganglioma carotídeo maligno. A propósito de un caso

2019

Resumen Los tumores del cuerpo carotideo son neoplasias poco frecuentes, de lento crecimiento, muy destructivos y vascularizados, que tienen un origen neuroectodermico. Los tumores malignos representan el 5-13% de los casos y presentan un comportamiento agresivo local con infiltracion de los ganglios linfaticos adyacentes o metastasis a distancia. Presentamos el caso de un varon de 60 anos al que en el estudio por dolor y parestesias en miembro superior se le realiza una resonancia magnetica donde se visualiza una gran tumoracion en el espacio carotideo izquierdo, la cual se biopsio obteniendo el diagnostico histologico de paraganglioma. Al realizar el estudio de extension se identifico la …

Development of a fast characterization setup for radionuclide generators demonstrated by a 227Ac-based generator

2021

Abstract The development of a setup for a fast online characterization of radionuclide generators is reported. A generator utilizing the mother nuclide 227Ac sorbed on a cation exchange resin is continuously eluted by using a peristaltic pump. To allow continuous and pulse-free elution of a large volume over extended time periods a 3D-printed interface designed to remove pressure-oscillations induced by the pump was placed between pump and generator column to ensure undisturbed generator elution. The eluate of the generator is passed through a 3D printed flow cell placed inside a borehole Na(Tl)-scintillation detector for high counting efficiency. Alternatively, a HPGe detector suitable for…

Simple eddy current compensation by additional gradient pulses

2018

Estimation of Location and Activation Time of Purkinje Myocardial Junctions from Sparse and Noisy Endocardial Electrical Samples

2017

The activation of the myocardial muscle is triggered by Purkinje-myocardial junctions (PMJs), which are the terminal sites of the specialised cardiac conduction system (CCS). Obtaining the location of the PMJs and other sources of endocardial ectopic activity would be desirable for building computer models of cardiac electrophysiology and planning ablation interventions. We present a method to estimate the location and activation times of endocardial electrical sources in a 3D model of the ventricles. The algorithm requires a set of discrete electrical samples on the endocardium, which can include errors in location and activation time. The estimated sources are properly placed with a locat…

Anatomia e patologia del labirinto membranoso studio con sequenze RM sensibili al flusso

1994

Nonostante i deludenti esordi nella valutazione delle strutture labirintiche costituenti l'orecchio interno, la risonanza magnetica costituisce oggi, grazie anche al miglioramento dell'hardware e del software disponibili, una modalità diagnostica di grande efficacia non solo nell'analisi della patologia espansiva o infiammatoria coinvolgente il VII ed VIII nervo cranico, ma anche nella valutazione delle alterazioni patologiche del segnale endolabirintico in rapporto a focolai emorragici o, come recentemente dimostrato mediante uso di Gd-DTPA, nell'analisi delle alterazioni a carico della capsula oticanella fase spongiotica dell'otosclerosi. Tuttavia, lo scarso contrasto esistente tra liqui…