Practical iterative reconstruction methods for quantitative cardiac SPECT image reconstruction

Summary form only given. The authors investigate the practical implementation of iterative reconstruction methods to improve the quality and quantitative accuracy of cardiac single photon emission computed tomography (SPECT) images over the filtered backpropagation (FB) algorithm. A cardiac-chest phantom based on a patient CT scan and Tl-201 uptake data was used in the study. Projection data were generated which included the effects of nonuniform attenuation detector response, scatter and noise. Use was made of the iterative Chang algorithm with nonuniform attenuation compensation only, the iterative maximum likelihood-expectation maximization (ML-EM) and WLS-CG methods, and variations of the WLS-CG methods, including the use of the FB or Chang reconstructed image as initial estimate and filtering to suppress noise amplifications at high iteration number. The mean-square-error over the region of the heart and the normalized standard deviation over a background region were used to evaluate the different reconstruction methods. It was found that, using the Chang reconstructed image as the initial estimate in the WLS-CG method together with filtering between iterations, cardiac SPECT images with good quality and quantitative accuracy can be obtained in a few iterations