<title>Dynamic estimation of left-ventricular ejection fraction</title>

Abstract

We investigate a method to obtain a dynamic estimate of left ventricular ejection fraction from a gated set of planar myocardial perfusion images. Ejection fraction is defined as the ratio of the fully contracted left-ventricular volume to the fully expended left-ventricular volume and is known as an effective gauge of cardiac function. This method is proposed as a safer and more cost-effective alternative to currently used radionuclide ventriculographic based techniques. To formulate this estimate of ejection fraction, we employ geometric reconstruction and recursive estimation techniques. The left ventricle is modelled as a dynamically evolving three- dimensional ellipsoid. The left-ventricular outline observed in the myocardial perfusion images are then modelled as two-dimensional ellipsoids, obtained as projections of the former three- dimensional ellipsoid. The ellipsoid that approximates the left ventricle is reconstructed using Rauch-Tung Striebel smoothing which combines the observed temporal set of projection images with an evolution model to produce the best estimate of the ellipsoid at any point in time given all the data. This investigation includes estimation of ejection fraction from both simulated and real data.