Analytic And Iterative Reconstruction Algorithms In Myocardial Perfusion Spect: A Comparative Study
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Date
2012-04
Authors
Mansor, Mohd Syahir
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
The purpose of this study was to compare the quality of images reconstructed using analytic or more commonly known as filtered back-projection (FBP) and iterative method based on maximum-likelihood expectation maximization (ML-EM) in myocardial perfusion (MP) single photon emmision computed tomography (SPECT). Phantom studies using different ratios of background activity to target activity (BTR) of 0.2, 0.4, 0.6 and 0.8 were used to simulate the different ratios of the activity in the lung to the activity in the heart (LHR) for patients undergoing MP SPECT. For FBP, the cut off frequency ranged from 0.4 to 0.6 cycle/ cm with order of 5 were used to reconstruct the image while for ML-EM method the number of iterations examined were 4, 8, 12, 16, 24, 32, 40, 48, 64, 80, 96 and 128. Contrast recovery coefficient (CRC) and signal to noise ratio (SNR) were assessed for image quality to determine the optimum reconstruction parameters. The optimum filter parameters for FBP was 0.4 cycle/ cm with order of 5 and 40 iterations were recommended for ML-EM method. MP SPECT raw data from two patients of each LHR group were used for image reconstruction using the optimized reconstruction parameters for image quality comparison between the two methods. The image quality parameters evaluated were artefact, noise and sharpness. The Kruskal Wallis test was used to compare the image quality among different LHR values (0.2, 0.4, 0.6 and 0.8) for each reconstruction method. Then, the image quality produced by FBP and ML-EM was compared using Wilcoxon signed rank test for each LHR groups. Finally, the image quality produced by FBP and ML-EM was compared using
Wilcoxon signed rank test independent of LHR values. Based on the statistical analyses, there was no significant difference in image quality between different LHR values for both reconstruction methods (p>0.05, Kruskal Wallis). The image quality obtained by both image reconstruction methods was about the same for each LHR values (p>0.05, Wilcoxon rank signed test). Regardless of LHR values, no significant difference in image quality was observed between the two methods (p>0.05, Wilcoxon rank signed test). Based on the data, the iterative reconstruction algorithm (ML-EM) could be an alternative for SPECT slices reconstruction in MP SPECT.
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Keywords
Analytic and iterative reconstruction algorithms , in myocardial perfusion spect