Michael T. LeFree

Application of a Computerized Image-Intensifier Radionuclide Imaging System to the Study of Regional Left Ventricular Dysfunction

A light-sensitive, self-scanning, silicon diode array has been used to interface an image-intensifier gamma camera to a digital computer for performing high resolution dynamic radionuclide angiocardiography. The spatial resolution of this image-intensifier camera (IIC) system, which does not perform pulse-height analysis, is somewhat worse than that of the Anger camera (AC) at count-rates below 50 K cps. Between 50 K and 250 K cps the IIC demonstrates linear countrate performance without the distortion and resolution loss associated with the AC. The ability of the IIC to maintain resolution at extremely high count-rates is of particular value for performing first transit, radionuclide bolus washout studies of cardiac dynamics. The high contrast and increased information density achieved by this approach provides accurate measurement of left ventricular volume and its first derivative with respect to time as verified by direct comparison with left cine ventriculography (cine). For the study of regional left ventricular wall motion, radionuclide images corresponding to end-diastole and end-systole have been used to compute functional images which accurately describe abnormally contracting segments of the left ventricular wall. The ability to study left ventricular volume and segmental wall motion without left heart catheterization is of significant diagnostic and investigative value.