Biomedical subjects
P R Schvartzman
Publications and source records attributed to P R Schvartzman.
Clinical validation of an automated boundary tracking algorithm on cardiac MR images.
The goal of this research was to develop an automated algorithm for tracking the borders of the left ventricle (LV) in a cine-MRI gradient-echo temporal data set. The algorithm was validated on four patient populations: healthy volunteers and patients with dilated cardiomyopathy (DCM), left ventricular hypertrophy (LVH), or left ventricular aneurysm (LVA). A full tomographic set (approximately 11 slices/case) of short-axis images through systole was obtained for each patient. Initial endocardial and epicardial contours for the end-diastolic (ED) and end-systolic (ES) frames were manually traced on the computer by an experienced radiologist. The ED tracings were used as the starting point for the algorithm. The borders were tracked through each phase of the temporal data set, until the ES frame was reached (approximately 7 phases/slice). Peak gradients along equally spaced chords calculated perpendicular to a centerline determined midway between the endocardial and epicardial borders were used for border detection. This approach was tested by comparing the LV epicardial and endocardial volumes calculated at ES to those based on the manual tracings. The results of the algorithm compared favorably with both the endocardial (r2 = 0.72 - 0.98) and epicardial (r2 = 0.96 - 0.99) volumes of the tracer.
Imaging of cardiac and paracardiac masses.
Magnetic resonance imaging (MRI) and computed tomography (CT) are important imaging modalities for the noninvasive characterization of cardiac and paracardiac masses. They are, in general, superior to other modalities (e.g., echocardiography) in their ability to delineate the exact location and the extent of the lesion and to demonstrate the effects of the lesion on surrounding structures. MRI and CT may also be helpful in suggesting a specific diagnosis, because some tumors have rather characteristic locations and appearances. In addition, both modalities can be extremely helpful in both treatment planning and posttreatment follow-up because they are noninvasive, reproducible, and enable detection of residual or recurrent mass.
Normal values of echocardiographic measurements. A population-based study.
OBJECTIVE: To describe echocardiographic measurements and left ventricular mass in a population sample of healthy adults inhabitants of the urban region of Porto Alegre. METHODS: An analytical, observational, population-based, cross-sectional study was done. Through a multi-stage probability sample, 114 individuals were selected to be submitted to a M-mode and two-dimensional echocardiogram with color Doppler. The analyses were restricted to healthy participants. Echocardiographic measurements were described by mean, standard deviation, 95 percentile and 95% confidence limits. RESULTS: A total of 100 healthy participants, with several characteristics similar to those from the original population, had a complete and reliable echocardiographic examination. The measurements of aorta, left atrium, interventricular septum, left ventricle in systole and diastole, left posterior wall and left ventricular mass, adjusted or not for body surface area or height, were significantly higher in males. The right ventricle size was similar among the genders. Several echocardiographic measurements were within standard normal limits. Interventricular septum, left posterior wall and left ventricular mass, adjusted or not for anthropometric measurements, and aortic dimensions had lower mean and range than the reference limits. CONCLUSION: The means and estimates of distribution for the measurements of interventricular septum, left posterior wall and left ventricular mass found in this survey were lower than those indicated by the international literature and accepted as normal limits.
[Use of transesophageal echocardiography in cardioversion of atrial fibrillation].
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