20 documents found, page 1 of 2
Registration of Consecutive Frames From Wireless Capsule Endoscopy for 3D Motio...
Oliveira, Marina; Araújo, Helder; Figueiredo, Isabel N.; Pinto, Luís; Curto, Eva; Perdigoto, LuísWireless Capsule Endoscopy (WCE) is a non-invasive medical procedure devised for painless in vivo inspection of the gastrointestinal (GI) tract. It is especially valuable for the examination of the small intestine since it is dif cult to reach by traditional endoscopic procedures. The setup includes a camera with an embedded light source and a circuit capable of acquiring and transmitting the video. The main ch...
Wireless Capsule Endoscope Location and a Robotic Validation Experiment
Figueiredo, Isabel N.; Pinto, Luís; Perdigoto, Luís; Oliveira, Marina; Araújo, Hélder; Figueiredo, Pedro N.We present results concerning the validation of a novel approach for wireless capsule endoscope localization, using as ground truth a simulated biological/mechanical environment experiment. The approach relies essentially on image-based methods. It involves a hybrid multi-scale affine and elastic image registration procedure which is afterwards appropriately complemented with calibration and visual odometry tec...
Optical flow with fractional order regularization: Variational model and soluti...
Bardeji, Somayeh Gh.; Figueiredo, Isabel N.; Sousa, ErcíliaAn optical flow variational model is proposed for a sequence of images defined on a domain in R^2. We introduce a regularization term given by L^1 the norm of a fractional differential operator. To solve the minimization problem we apply the split Bregman method. Extensive experimental results, with performance evaluation, are presented to demonstrate the effectiveness of the new model and method and to show th...
Automated retina identification based on multiscale elastic registration
Figueiredo, Isabel N.; Moura, Susana; Neves, Júlio S.; Pinto, Luís; Kumar, Sunil; Oliveira, Carlos M.; Ramos, João D.In this work we propose a novel method for identifying individuals based on retinal fundus image matching. The method is based on the image registration of retina blood vessels, since it is known that the retina vasculature of an individual is a signature, i.e., a distinctive pattern of the individual. The proposed image registration consists of a multiscale affine registration followed by a multiscale elastic ...
Homogenization Model for Aberrant Crypt Foci
Figueiredo, Isabel N.; Leal, Carlos; Romanazzi, Giuseppe; Engquist, BjornSeveral explanations can be found in the literature about the origin of colorectal cancer. There is, however, some agreement on the fact that the carcinogenic process is a result of several genetic mutations of normal cells. The colon epithelium is characterized by millions of invaginations, very small cavities, called crypts, where most of the cellular activity occurs. It is agreed in the medical community tha...
Automated lesion detectors in retinal fundus images
Figueiredo, Isabel N.; Kumar, Sunil; Oliveira, Carlos M.; Ramos, João Diogo; Engquist, BjornDiabetic retinopathy (DR) is a sight-threatening condition occurring in persons with diabetes, which causes progressive damage to the retina. The early detection and diagnosis of DR is vital for saving the vision of diabetic persons. The early signs of DR which appear on the surface of the retina are the dark lesions such as microaneurysms (MAs) and hemorrhages (HEMs), and bright lesions (BLs) such as exudates....
Computer-assisted bleeding detection in wireless capsule endoscopy images
Figueiredo, Isabel N.; Kumar, Sunil; Leal, Carlos; Figueiredo, Pedro N.Wireless capsule endoscopy (WCE) has revolutionised the diagnosis and treatment of gastrointestinal tract, especially the small intestine where traditional endoscopies cannot reach. However, this new technology leads to the inspection of a large number of images, which is a time-consuming process and also too hard by naked eyes for doctors. In this paper, we propose a new computerised method for bleeding detect...
Automatic Polyp Detection in Pillcam Colon 2 Capsule Images and Videos: Prelimi...
Figueiredo, Pedro N.; Figueiredo, Isabel N.; Prasath, Surya; Tsai, RichardBackground. The aim of this work is to present an automatic colorectal polyp detection scheme for capsule endoscopy. Methods. PillCam COLON2 capsule-based images and videos were used in our study. The database consists of full exam videos from five patients. The algorithm is based on the assumption that the polyps show up as a protrusion in the captured images and is expressed bymeans of a P-value, defined by g...
Image-driven parameter estimation in absorption-diffusion models of chromoscopy
Figueiredo, Isabel N.; Figueiredo, Pedro; Almeida, NunoThe administration of dyes and subsequent examination, with a colorimetry visual criterium, is a gastroenterology procedure for distinguishing, in endoscopic images, normal and aberrant colonic crypts. These are thought to be possible precursors of colon cancer. In this paper a combined image segmentation and parameter estimation model is proposed for in vivo colonic crypts’ images, obtained with chromoscopic c...
A coupled convection-diffusion level set model for tracking epithelial cells in...
Figueiredo, Isabel N.; Leal, Carlos; Leonori, Tommaso; Romanazzi, Giuseppe; Figueiredo, Pedro N.; Donato, M. ManuelColorectal cancer is initiated in colonic crypts as a consequence of alterations leading to the disruption of the normal colonic cellular process. We propose a new model, which couples a convection-di usion type equation with a level set equation, for tracking the time evolution of an epithelial cell set, inside a colonic crypt, until it reaches the top of the crypt. The convection-di usion equation describes t...