[unreadable] A valuable tool in the diagnosis of coronary artery disease is gated emission computed tomography (ECT) using either single photon ECT or positron emission tomography tracers. These methods provide 3D images of myocardial perfusion or metabolism at discrete phases of the cardiac cycle. Relative to non-gated imaging, gated ECT reduces motion blur and allows an estimation of important functional parameters such as ejection fraction and wall motion. However, because individual gated ECT images are obtained using data from only a fraction of the cardiac cycle, they have increased noise relative to non-gated images, which reduces image quality and introduces uncertainty into the motion analysis. The foremost goal of this proposal is to develop processing methods for gated ECT that improve the quality of the reconstruced image in a way that also improves the accuracy of the cardiac motion analysis. The underlying framework of these processing methods is to perform in parallel (a) image reconstruction, and (b) motion estimation, thus flowing one estimation process to help stabilize the other. Our overall hypothesis is that such a joint estimation procedure provides improved accuracy and precision relative to current methods of independent reconstruction and motion estimation. The specific aims of this proposal are the following: 1. To develop simultaneous reconstruction and motion analysis for a two frame system, 2. To develop simultaneous estimation methods using a continuous-time, periodic model of cardiac contractile motion, 3. To develop simultaneous estimation methods that incorporate both contractile and respiration-induced cardiac motion analysis. The proposed methods will be evaluated using phantoms and patient data considering both the accuracy of calculated functional parameters and the ability to detect myocardial defects by humans. [unreadable] [unreadable]