Spatio-temporal reconstruction for gated cardiac spect

In myocardial perfusion imaging using single photon emission computed tomography (SPECT), gated acquisition is often used in order to deal with blur caused by cardiac motion in the resulting images. While this can provide useful information about the myocardial function, it also inevitably leads to reduced signal-to-noise ratio in the acquired data due to gating. In this work, we aim to investigate and evaluate image reconstruction methods for improving the quality of reconstructed images in cardiac gated SPECT imaging.;First, we propose a spatio-temporal (aka 4D) reconstruction procedure for gated images based on use of the discrete Fourier transform (DFT) basis functions. The gated images are reconstructed through determination of the coefficients of the Fourier representation. Our simulation results demonstrate that use of DFT-basis functions in gated imaging can improve the accuracy of the reconstruction.;Next, we develop and demonstrate a fully 5D (3D space plus time plus gate) reconstruction procedure for cardiac gated, dynamic SPECT imaging, where the goal is to obtain an image sequence from a single acquisition showing simultaneously both cardiac motion and tracer distribution change. Our simulation results demonstrate that the 5D reconstruction procedure can yield gated dynamic images which show quantitative information for both perfusion defect detection and cardiac motion.;Based upon the above success, we also study the saliency of 5D images for detection of perfusion defects. We explore several methods for efficient characterization and visualization of information pertinent to perfusion defects in a 5D image sequence. We apply various metrics to quantify the degree to which perfusion deficits can be detected. We show that these metrics can be used to produce new types of visualizations for wall motion and perfusion information.;Finally, we also investigate a direct reconstruction approach to determine a sequence of gated, kinetic parameter images from a single acquisition. To combat the greatly under-determined nature of the problem, we introduce smoothness constraints to exploit the similarity both spatially and temporally among the different gates.