Rubén Medina

Three-dimensional reconstruction of the left ventricle from two angiographic views: an evidence combination approach

Clinical interventional hemodynamic studies quantify the ventricular function from two-dimensional (2-D) X-ray projection images without having enough information of the actual three-dimensional (3-D) shape of this cardiac cavity. This paper reports a left ventricle 3-D reconstruction method from two orthogonal angiographic projections. This investigation is motivated by the lack of information about the actual 3-D shape of the cardiac cavity. The proposed algorithm works in 3-D space and considers the oblique projection geometry associated with the biplane image acquisition equipment. The reconstruction process starts by performing an approximate reconstruction based on the Cylindrical Closure Operation and the Dempster-Shafer theory. This approximate reconstruction is appropriately deformed in order to match the given projections. The deformation procedure is carried out by an iterative process that, by means of the Dempster-Shafer and the fuzzy integral theory, combines the information provided by the projection error and the connectivity between voxels. The performance of the proposed reconstruction method is evaluated by considering first the reconstruction of two 3-D binary databases from two orthogonal synthetized projections, obtaining errors as low as 6.48%. The method is then tested on real data, where two orthogonal preprocessed angiographic images are used for reconstruction. The performance of the technique, in this case, is assessed by means of the projection error, whose average for both views is 7.5%. The reconstruction method is also tested by performing the 3-D reconstruction of a ventriculographic sequence throughout an entire cardiac cycle.

A 3-D Multi-modality Image Framework for Left Ventricle Motion Analysis

In this paper, a multiplatform computing tool for left ventricle (LV) motion analysis from three-dimensional cardiac images is described. The tool uses as input data, LV geometric representations constructed from multislice computed tomography databases, and LV 3D models reconstructed from biplane angiography projections. A non-rigid bidimensional correspondence algorithm is used to track a set of anatomical landmarks extracted from LV surfaces. The objective is to establish the correspondence between contours on consecutive instants of time. From the estimated correspondence, parameters associated with cardiac dynamical function are calculated. These parameters are useful for assessing cardiac pathologies. Among parameters considered are: torsion, radial contraction, longitudinal contraction, and the static motion representation based on LV longitudinal and radial slices, and their integration into a polar scheme known as bulls eye.

Open source cardiology electronic health record development for DIGICARDIAC implementation

This article presents the development of a Cardiology Electronic Health Record (CEHR) system. Software consists of a structured algorithm designed under Health Level-7 (HL7) international standards. Novelty of the system is the integration of high resolution ECG (HRECG) signal acquisition and processing tools, patient information management tools and telecardiology tools. Acquisition tools are for management and control of the DIGICARDIAC electrocardiograph functions. Processing tools allow management of HRECG signal analysis searching for indicative patterns of cardiovascular pathologies. Telecardiology tools incorporation allows system communication with other health care centers decreasing access time to the patient information. CEHR system was completely developed using open source software. Preliminary results of process validation showed the system efficiency.

A Level-set Segmentation Approach for 4-D Cardiac Images

Cardiac diseases are one of the main causes of death in the World. This has motivated an important research effort aiming at the development of accurate tools for improving diagnosis and treatment. Recently, the Multi-Slice Computerized Tomography (MSCT) has emerged as a new source of 4D cardiac images that enables recording of cardiac shapes and their dynamical behavior during the cardiac cycle. This imaging technology requires the development of accurate techniques for analyzing and quantifying these images. This work presents the development of a software tool that enables a semi-automatic segmentation of cardiac cavities in MSCT images. The system core is a Level-Set algorithm. According to this algorithm, the contour is embedded as a zero level set of a higher dimensional level set function whose evolution described by a differential equation is performed considering features extracted from the images. The segmentation tool allows the user to define an initial rough segmentation by manual tracing of several contours in the 3D MSCT database. This approximate segmentation is improved using the level-set algorithm. The validation is performed by comparing the segmentation obtained using the level-set based algorithm with respect to the segmentation performed by medical experts. First results based on left ventricle extraction are promising.

Using morphological and clustering analysis for left ventricle detection in MSCT cardiac images

In this paper, an unsupervised approach based on non-linear filtering and region growing techniques to obtain the endocardial surface is proposed. The filtering stage is performed using mathematical morphology operators in order to improve the left ventricle cavity information in multi slice computerized tomography images. A seed point located inside the cardiac cavity is used as input for the region growing algorithm. This seed point is propagated along the image sequence to obtain the left ventricle surfaces for all instants of the cardiac cycle. The method is validated by comparing the estimated surface with respect to left ventricle shapes drawn by a cardiologist. The average error obtained was 1.38 mm.

Parámetros que mejor identifican la presencia de la miocardiopatía chagásica a partir del electrocardiograma superficial

This paper reports the evaluation of a high fidelity ECG hardware/software (CardioSoft, Houston, TX), in a group of chronic chagasic patients.