Measurement of Myocardial Blood Flow in Human by Thallium Scintigraphy: A Quantitative Approach

Coronary Artery Disease is responsible for nearly thirty five percent of all deaths in this country. The use of radioactive tracers in clinical cardiology was introduced many years ago to study the velocity of blood through the heart tissue. At present, many radionuclides are used in methods for evaluating coronary artery disease and myocardial perfusion. This thesis attempts to optimize one of these methods known as Thallium Scintigraphy. Thallium is a radioisotope which is taken up by the heart tissue at a rate which is proportional to the blood flow through the heart tissue. Therefore, tissue which is underperfused, and thus not receiving enough oxygen and nutrients to function properly, can be detected by using a gama camera which images the Thallium distribution. A clinician then qualitatively evaluates the image to locate underperfused areas. Problems arise, when qualitatively evaluating an image such as interobserver variability and observer dependence on display. This work provides a method which can quantify these images and analyze them quantitatively. The method is tested in a clinical setting in order to evaluate the sensitivity in disease detection as well as its usefulness in a clinical environment. We have studied a special group of single vessel diseased Patients (mild disease) in order to determine the sensitivity of our method compared to the quite low sensitivity of qualitative evaluation of images. Our method predicted 74 patients were diseased out of 81 single vessel diseased patients. This defines a sensitivity of 91% for our quantitative method