| Coronary artery disease (CAD), which involves narrowing of the vessels supplying blood to the heart, is the leading cause of death in the United States. Complete recovery from CAD can be achieved by early and accurate diagnosis of the disease leading to timely and appropriate treatment. Stress testing is a common approach for diagnosing myocardial ischemia, a state of blood supply and demand imbalance resulting from CAD. Physical exercise or pharmacologic agents raise the heart's oxygen demand, failure to meet which sets in myocardial ischemia leading to left ventricular (LV) dysfunction. Stress echocardiography (echo) and stress single photon emission computed tomography (SPECT), which provide complementary anatomical and perfusion information about the heart, remain the two most commonly prescribed cardiac stress testing procedures. Stress echo manifests the LV dysfunction as abnormal myocardial wall motion and thickening, whereas stress SPECT shows the myocardial perfusion defects. Despite their frequent clinical utilization, however, these two procedures remain limited in their sensitivity and specificity, and the diagnosis of CAD using either of these techniques individually is often ambiguous, necessitating costly invasive follow-up tests like cardiac catheterization. This dissertation focuses on development of accurate and automatic image analysis techniques that will enhance the utility of these images and increase the diagnostic accuracy of cardiac stress testing using echo and SPECT.; Real-time three-dimensional (RT-3D) ultrasound is an emerging innovation in imaging that is capable of scanning the entire left ventricle along with its complex motion in a few cardiac cycles. The clinical feasibility of 3D stress echocardiography, based on the powerful RT-3D ultrasound, has previously been documented. The first hypothesis in this dissertation is that a truly quantitative 3D stress echo procedure, that utilizes advanced quantitative image analysis techniques together with RT-3D ultrasound, is capable of overcoming many of the limitations of conventional stress echo and therefore improving diagnostic accuracy. The current research builds on the preliminary work (interactive visualization and registration of 3D echo) done within the group, and describes the development of a novel interactive and quantitative stress echo software that combines, for the first time, fully automatic tools for accurate pre-/post-stress image alignment, LV myocardial segmentation and quantification of global and regional LV function for RT-3D echo images. (Abstract shortened by UMI.)... |
