Comparison of 180/spl deg/ and 360/spl deg/ iterative reconstruction with non-uniform attenuation compensation for SPECT

This simulation study compares Tl-201, cardiac SPECT images reconstructed from 180/spl deg/ and 360/spl deg/ emission projection data, using iterative reconstruction with non-uniform attenuation compensation. The images reconstructed with attenuation compensation are compared to each other and to images reconstructed without attenuation compensation. Using a mathematical phantom of the human thorax, Monte Carlo simulation is used to produce both 180/spl deg/ (45/spl deg/ RAO to 45/spl deg/ LPO) and 360/spl deg/ SPECT projection data for a 74 keV radionuclide (T1-201). Included in the simulation are the effects of non-uniform attenuation, detector response, and scatter. The 180/spl deg/ and 360/spl deg/ data were taken over 64 and 128 angles respectively, assuming the same total acquisition time for both. The simulated projection data were reconstructed with nonuniform attenuation compensation using the ML-EM algorithm for 50 iterations and, for comparison, were also reconstructed without attenuation compensation using the filtered backprojection method with a ramp filter. Transaxial slices of the reconstructed images, image profiles and Bull's-eye plots all show that images reconstructed with attenuation compensation, unlike those reconstructed without attenuation compensation, are essentially the same in the myocardial region for the 180/spl deg/ and 360/spl deg/ data, with few artifacts and similar image contrast. Furthermore, for the same total imaging time, the images reconstructed from the 180/spl deg/ data have slightly less noise in the myocardial region.<
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