L. Moura

A microcomputer-based cardiac mapping system for recurrent ventricular tachycardia surgery

The authors present a system which allows the mapping of the electrical activity of the heart, aiming at locating the ectopic focus when performing open heart surgery for recurrent ventricular tachycardia correction. This open-heart surgery system allows the acquisition and analysis of the electrical signal at up to 256 points on the heart surface at a given time, allowing 3-D maps of the electrical activation of the heart to be generated and displayed under user control. The experiments in dogs and the first surgery in humans have suggested that the system is safe, simple to use, reliable, and accurate.<<ETX>>

Estimation of myocardial kinetic energy in gated SPECT images

Conventional methods for the analysis of left ventricle (LV) wall motion are based on 2D images with many hardly fulfilled assumptions. The methods in use today suffer from several problems as they do not take into account three-dimensional (3D) information that can be provided by image modalities such as nuclear medicine and MRI. This work describes a method to quantify 3D LV motion by a series of 3D velocity vector fields that are computed automatically for each voxel on the sequence of 16 cardiac volumes. Using the velocity it is possible to estimate the kinetic energy for each voxel. The integration of this quantity over the LV muscle gives an estimate of the left ventricle wall kinetic energy. A curve representing the myocardial kinetic energy can be plotted and used as an indicator of cardiac conditions. The proposed method was applied to the study of normal and abnormal hearts. Results have shown that the curve pattern for hearts with infarct differs substantially from a normal heart.

3-D analysis of left ventricle dynamics

Describes a method which quantifies 3D LV motion by means of the optical flow technique extended to the voxel space. Motion is represented by a 3D velocity vector field which is computed for each voxel on the series of cardiac volumes. The algorithm developed has two steps: (1) the spatial and temporal derivatives of the 3D image brightness are computed, after the cardiac volumes have been convolved with a symmetrical Gaussian function filter; (2) The optical flow is computed as the solution to a linear algebraic system of equations whose coefficients are determined by the derivatives that were computed in (1). The velocity vector field estimated from a sequence of 3D images has been computed for normal and infarcted hearts obtained at InCors Nuclear Medicine Department.<<ETX>>

Myocardial motion estimation in gated-MRI using optical flow refined with scale-space

Although MR imaging techniques are able to show cardiac motion qualitatively, no information is provided about motion of the tissue within the epicardial and endocardial boundaries using standard procedures. This work describes a method to quantify the myocardial motion from 3D MR images based on Optical Flow technique. To improve derivatives estimation, a fundamental step in any Optical Flow implementation, the authors applied the one parameter Gaussian derivative operator, obtained from the scale-space approach. The method quantifies the 3D LV motion by a series of 3D velocity vector fields and this vectorial information is used to estimate the scalar parameter. Myocardial kinetic energy. The evolution of the kinetic energy parameter during the cardiac cycle may represent the cardiac conditions.

Extraction of cardiac structures through the incorporation of a priori knowledge in a multiscale approach

The task of simultaneous segmentation of complex anatomical structures such as the cardiac organs is not trivial. The authors have divided this task in two phases. (A) extraction of the desired structures, that includes a rough segmentation, (B) a post-processing phase for segmentation refinement. In this work the authors are addressing the extraction phase using an image representation based on a scale space approach. The Scale Space Primal Sketch representation is based on image structures called blobs, that represent regions in which image counts are higher or lower than their surrounding background. The linking of these structures across scale space allows the analysis of the characteristics and behavior of these blobs. Stable blobs are supposed to represent important features of the image and significance measurement rates based on it allows the classification of these structures. This methodology was implemented and applied to MRI thoracic images. It allowed the extraction of the cardiac structures, but also extracted other undesired features. In order to overcome this problem, the authors refined the criteria for the extraction of significant blobs from the Scale Space Primal Sketch by including a priori information on the significance measurement rate.

A multiscale method to isolate cardiac structures in MRI

Magnetic resonance images may become a more important tool for the analysis of congenital heart disease once they permit a detailed view of 3D cardiac anatomy. They are not yet widely used in this sense mainly because the visualization depends on a previous segmentation step, which is mostly performed manually in a tedious and time consuming procedure. In this work the authors are addressing the segmentation of cardiac structures using a multiscale approach. Using the linear scale-space is possible to obtain representation from which important structures present in the image can be obtained as well as the scales where they become more evident. The authors implemented the scale space primal sketch to describe cardiac structures obtained from 3D MRI studies.

Quantification of myocardial kinematics in perfusion images from gated SPECT

Left ventricle contractile abnormalities can be an important manifestation of coronary artery disease. The abnormalities in wall motion may represent ischemia or infarction of myocardium. This kind of disease is often regional. It is a fundamental goal of many cardiac imaging modalities and image analysis methods to measure the regional function of the left ventricle (LV). In this work we describe a method to quantify the 3D myocardial kinetic energy (ke) via polar map or ke bulls eye obtained from gated SPECT images. For each slice a maximum-energy profile is generated by dividing the LV into sectors and taking the highest voxel value within a sector. The map profiles are plotted as concentric circles onto a polar map. Specific sectors show the regional variations of the ke on the LV wall. The current research includes a comparison of ke bulls eye patterns for normal and abnormal hearts as well as the discrimination capability for the proposed method.

Glossopharyngeal Neuralgia: Case Report

Glossopharyngeal neuralgia (GPN) is an unusual cause of facial pain, corresponding to approximately 0.2-1.3%. Patients usually presents with facial pain associated with daily life activities (cough, swallow) and in severe cases with syncop. Epidemiology of the pathology demonstrates controversy about the predominance of the male, being consensus from patients over 50 years. We present a case report of a 51 patient diagnosed and treats for this rare disease with good outcome.