Evaluation of Iterative Reconstruction Based Resolution Recovery (OSEM - RR) Combined With Attenuation and Scatter Corrections in Myocardial Perfusion Imaging

Introduction: Myocardial perfusion imaging (MPI) procedures using single photon computed tomography (SPECT) is well established noninvasive imaging technique and widely used to evaluate patients with known or suspected coronary artery disease (CAD). Several studies have shown the strong diagnostic and prognostic value of SPECT MPI. However, image degrading factors, scatter, attenuation and depth dependent collimator response are the main source of image quality degradation in MPI. Hence, great attention has been given to those factors to be incorporated in the reconstruction algorithms. Corrections for image degrading factors find their way to be applied in the clinical routine through development of both reconstruction algorithm and computers hardware. Applying the correction for those degrading factors helped to greater extent to improve the image quality and diagnostic accuracy of MPI. Method: The study was performed using standard cardiac phantom with two cold defects.The phantom was placed inside the Jaczack cylindrical phantom. Clinically relevant activity was injected into myocardium walls and its background.Results: When compared to analytical techniques, iterative reconstruction (IR) showed better performance in terms of contrast to noise ratio (CNR) and defect contrast resolution especially with gradual correction of SPECT degrading factors. However, this was associated with slight increase in image noise as demonstrated by uniformity and coefficient of variation (CoV) analysis. There was also a trend towards an improvement of defect contrast resolution in transmural compared to non - transmural defect. Conclusion: The results showed more insights on how iterative (with different corrections) and analytical techniques handle image noise, defect contrast, CNR with remarkable differences appeared on apical versus basal slices and transmural versus non- transmural perfusion defects. This will have significant implications on quantitative perfusion parameters derived from the chosen reconstruction algorithm.