Comparison of FORE, OSEM and SAGE algorithms to 3DRP in 3D PET using phantom and human subject data

Using phantom and human subject data, the authors have compared a number of reconstruction algorithms to the current “gold standard” method, 3D Reprojection Method (3 DRP), in an effort to validate them as practical 3D reconstruction alternatives for dynamic PET scanning. The algorithms evaluated were (a) Fourier Rebinning (FORE) followed by 2D Filtered Back Projection (2D FBP), (b) FORE followed by Ordered Subsets Expectation-Maximization (OSEM) and (c) FORE followed by Space Alternating Generalized Expectation-Maximization (SAGE). The main benefits of these methods are two-fold: significantly shorter reconstruction times and improved signal-to-noise ratio at matched resolution for the iterative schemes. The authors demonstrate that FORE+2D FBP can replace 3 DRP with no significant impact on subsequent data analysis. In particular, distribution volume ratios (DVRs) obtained with FORE+2D FBP differed from those obtained with 3 DRP by 0.3±0.7% (n=33) and -0.7±1.1% (n=27) for cortical and cerebellar input functions, respectively. Both OSEM and SAGE performed well compared to 3 DRP, with improved noise characteristics and DVR differences of <3%