Diego Jugo

Markov random field modeling for three-dimensional reconstruction of the left ventricle in cardiac angiography

This paper reports on a method for left ventricle three-dimensional (3-D) reconstruction from two orthogonal ventriculograms. The proposed algorithm is voxel-based and takes into account the conical projection geometry associated with the biplane image acquisition equipment. The reconstruction process starts with an initial ellipsoidal approximation derived from the input ventriculograms. This model is subsequently deformed in such a way as to match the input projections. To this end, the object is modeled as a 3-D Markov-Gibbs random field, and an energy function is defined so that it includes one term that models the projections compatibility and another one that includes the space-time regularity constraints. The performance of this reconstruction method is evaluated by considering the reconstruction of mathematically synthesized phantoms and two 3-D binary databases from two orthogonal synthesized projections. The method is also tested using real biplane ventriculograms. In this case, the performance of the reconstruction is expressed in terms of the projection error, which attains values between 9.50% and 11.78% for two biplane sequences including a total of 55 images

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.

Non-linear dynamics in heart rate variability of normal subjects and chagasic patients

Tachograms of two groups, one consisting of 15 chagasic patients (Group II) and the second group consisting of 18 healthy persons as a control group, were investigated. The tachograms (R-R intervals) were obtained from high resolution ECG. Statistical analysis of the first Lyapunov exponent and complexity changes through symbolic dynamics showed that parameters obtained from non-linear analysis could be used to discriminate between chagasic patients and healthy persons.

Reconstruction of three-dimensional cardiac shapes in biplane angiography: a fuzzy and evolutionary approach

A 3D reconstruction method for the left ventricle is proposed. The reconstruction is performed from true preprocessed images acquired in biplane angiography, by working directly in the 3D space and by considering the real acquisition geometry. The reconstruction method includes two stages. The first stage provides an approximate reconstruction for the ventricle shape. Several attributes from the ventriculographic images are used to define the fuzzy sets describing the ventricle, its contour and the background region. Combination of each pair of sets according to the fuzzy relation cylindrical closure operation and the Dempster-Shafer theory, allows an approximate binary shape to be found. The second stage improves the reconstruction by progressively deforming the initial shape by using a simple genetic algorithm (SGA). The SGA optimizes an objective function that measures the projection error and includes a connexity constraint between voxels of the object.

Nuevos métodos de análisis de la Variabilidad de la Frecuencia Cardiaca

This work describes new methods of analysis of heart rate variability whose efficiency has been demonstrated. It begins defining term HRV, continuous with a brief summary of the traditional methods of analysis of HRV. Finally describe results obtained when applying the methods of Transformed of Lomb, Detrended Fluctuation Analysis, and Symbolic Dynamics to a group of chronic chagasic patients.

Chronic chagasic patients classification using normalized cumulants

This work presents a study about normalized cumulants for quantifying the variations of the spectral temporal mapping obtained from signal-average electrocardiogram (SAECG). The parameter obtained from normalized cumulants estimation can be used in spectral turbulence analysis and so it helps to resolve the problem of chronic chagasic patients classification in early stages.