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Diagnosing complex heart malformations require the analysis of local heart motion. This paper presents a method for measuring local motion in a sequence of 2D echographic heart images. The heart cavities are segmented using an implicit geometric active contour robust to speckle. A combined rigid and non-rigid image registration method is then used to estimate the motion field. The cavity segmentation...
An image database of echocardiograms, EVALECHOCARD, dedicated to regional wall motion scoring is presented. It is devoted to become a public reference database, in order to develop an objective comparison on the same data of different computer vision packages aiming at scoring the regional wall motion. The database construction is described, including the data acquisition, the experts' annotation...
One of the main uses of the Intravascular Ultrasound (IVUS) images is tissue classification. Some of the most important tissues are calcium, fibrotic, and lipid plaque. Usually, this task is achieved using DICOM images. Here we exposed the use of reconstructed images from RF data to improve the classification process, because it is given the advantage of normalizing the images to a fixed parameter...
Brachial artery flow-mediated dilation (FMD) is a measure of endothelial dysfunction which is used to evaluate cardiovascular risk. A stand-alone video processing system based on a DSP board was developed in our lab to assess the brachial artery FMD from ultrasound images. In this paper the system is introduced and compared with the main methods and devices illustrated in literature. The available...
In this work a simulation study of T-wave alternans is proposed in order to determine the ability of TWA detectors to quantify the performance characteristics in terms of amplitude estimation accuracy. ECG signals were simulated by repeating a single beat, and by adding four types of noise each at two different levels of power. TWA episodes with different amplitudes and waveforms were added to the...
In this paper a simple and viable on-line method to transmit ECG under hardware restricted environments is derived and its performance illustrated in simulation studies. The proposed scheme makes use of an ECG signal lossless compression technique for the communications channel optimization. Obtaining a better compression rate guarantees both the sending costs and the memory resources reduction. Simulation...
A general purpose system for telediagnosis of the valvular condition of the heart by analysing the phonocardiographic (PCG) signals generated by the heart is presented in this article. The system includes two main parts: a processing stage and a compression stage. The first one is arranged as a modular hierarchical structure with different abstraction levels, and performs a complete analysis of the...
T-wave alternans (TWA) is an electrophysiologic phenomenon associated with an increased risk of death. ECG baseline wandering may prevent correct detection of TWA. The present study was designed to test the effectiveness of our newly developed heart-rate adaptive match filter (AMF) to remove baseline wanders and improve TWA detection. To this aim, both simulated and experimental (10 Holter ECGs of...
Baseline wandering interference misleads ECG anno- tators from accurate identification of the ECG features. Previous work that deals with baseline wandering removal requires the identification of the QRS complex or other ECG features prior to baseline removal. This paper proposes an adaptive Kalman filter for the real time removal of baseline wandering using a polynomial approximation independent...
This paper presents a novel and efficient algorithm of ECG compression in real time monitoring systems, updated with each new input signal sample. This algorithm tries to improve the compression ratio of the captured signal by means of an optimal noise threshold in terms of hardware complexity and memory requirements. Threshold estimation is computed, using the instantaneous standard deviation, in...
Recently, a new complexity measure, multiscale entropy (MSE), has been developed based on the quantification of heart rate fluctuations over a range of time scales. Here, we use the MSE algorithm to analyze the cardiac interbeat interval time series from patients with congestive heart failure (CHF) enrolled in the MUSIC study. Our hypothesis is that the heart rate time series from the patients who...
A computer-aided diagnosis method is reported that allows to objectively identify subjects with connective tissue disorders from sixteen-phase 4D (3D+time) aortic MR images. Our automated segmentation method combines level-set and optimal surface segmentation algorithms so that the final aortic surfaces in all 16 cardiac phases are determined in a single optimization process. The resulting aortic...
A robust model-based segmentation method for automatically detecting left ventricular endocardial borders in cardiac MRI short-axis slices is proposed. The method is evaluated with expert drawn contours on an extended dataset (83 cases). The contour detection involves the four steps: (a) A region of interest enclosing the left ventricle is computed using a size invariant circular Hough transform,...
The objective of this work is to evaluate the feasibility of using non-rigid registration techniques to estimates myocardial motion from CINE-MR images without user interaction. Myocardial displacement field was obtained using a pair-wise non rigid registration technique that computes incremental motion for every consecutive pair of images in the sequence. We use a semi-local parametric deformation...
We propose a simple normalized index (i.e. the percentage of positive variations between two successive samples, PV%) and a procedure based on surrogate data to detect irreversible time series. This index was applied to short term heart period variability series (-300 cardiac beats) derived from 10 young healthy humans at rest (R), during head-up tilt (T) and controlled respiration at 10, 15 and 20...
In magnetic resonance imaging (MRI), imaging a moving organ such as the heart requires a trigger so that successive scans can be synchronized. In the case of cardiac and respiratory imaging, the QRS complex of ECG is used as a trigger signal for MRI scan. But, gradient and radio frequency (RF) artifacts which are caused to static and dynamic field in MRI scanner cause interference in the ECG. Also,...
The aim of this work is to predict the spontaneous termination of atrial fibrillation (AF) episodes. The database includes three record groups: non-terminating AF (N), AF that terminates one minute after recording end (S), and AF that terminates immediately after recording end (T). A first goal consisted on separating N from T group records (event 1), and a second, for separating S from T records...
The proposed method detects fetal R waves on abdominal non-invasive records. An exponentially averaged pattern of the mother PQRST segment is obtained and subtracted. Subsequently the fetal R detector based on a Smoothed Nonlinear Energy Operator (SNEO) is applied to the residual signal. Finally, criteria about amplitude, heart rate and backward search are settled to correct false detections. To evaluate...
We developed infant-specific transformations of ECG leads and compared their performance with that achieved by transformations derived for adults. In particular, we studied the ability of 15 reduced lead sets consisting of Mason-Likar (M-L) limb leads and 2 precordial leads to predict the complete set of M-L 12 leads, plus right-sided, posterior, and orthogonal leads. The study population consisted...
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