Gerold Porenta

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Myocardial perfusion scintigraphy is a noninvasive diagnostic method for the evaluation of patients with suspected or proven coronary artery disease (CAD). We utilized case-based reasoning (CBR) methods to develop the computer-based image interpretation system SCINA which automatically derives from a scintigraphic image data set an assessment concerning the(More)
In this paper we present an extensive comparison between several feedforward neural network types in the context of a clinical diagnostic task, namely the detection of coronary artery disease (CAD) using planar thallium-201 dipyridamole stress-redistribution scintigrams. We introduce results from well-known (e.g. multilayer perceptrons or MLPs, and radial(More)
UNLABELLED In myocardial SPECT perfusion imaging, reorientation algorithms from transaxial image planes are used to generate short- and long-axis views of myocardial tracer uptake. We performed phantom experiments with 201Tl to delineate how image reorientation affects the results of quantitative image analysis. METHODS Thirty consecutive patient studies(More)
Neural networks are usually seen as obtaining all their knowledge through training on the basis of examples. In many AI applications appropriate for neural networks, however, symbolic knowledge does exist which describes a large number of cases relatively well, or at least contributes to partial solutions. From a practical point of view it appears to be a(More)
UNLABELLED Angiography of patients with typical chest pain reveals normal epicardial coronary arteries in about 20%. Coronary flow reserve (CFR) determination is an elaborate, but helpful, task, as only the evidence of microvascular disease enables appropriate therapy. We prospectively evaluated the incidence of a dysfunctional microcirculation and searched(More)
UNLABELLED This study presents and evaluates a model-based image analysis method to calculate from gated cardiac (18)F-FDG PET images diastolic and systolic volumes, ejection fraction, and myocardial mass of the left ventricle. The accuracy of these estimates was delineated using measurements obtained by MRI, which was considered the reference standard(More)
OBJECTIVE This study compared the diagnostic accuracy of different approaches of case-based reasoning (CBR) for the assessment of coronary artery disease (CAD) using thallium-201 myocardial perfusion scintigraphy in comparison with coronary angiography. METHODS AND MATERIAL For each scintigraphic image set, regional myocardial tracer uptake was obtained(More)
UNLABELLED The purpose of this study was to evaluate myocardial electrocardiography (ECG)-gated 13N-ammonia (13N-NH3) PET for the assessment of cardiac end-diastolic volume (EDV), cardiac end-systolic volume (ESV), left ventricular (LV) myocardial mass (LVMM), and LV ejection fraction (LVEF) with gated 18F-FDG PET as a reference method. METHODS ECG-gated(More)
Disorders of the basal ganglia and the extrapyramidal motor system exhibit an imbalance of neurotransmitter concentrations in affected neurons. For three synapses with dopamine, acetylcholine, and gamma-amino butyric acid (GABA), mathematical models of synaptic transmission are developed. To describe the kinetics of transmitter substances, compartment(More)