Comparison between OSEM and FBP reconstruction algorithms for the qualitative and quantitative interpretation of brain DAT-SPECT using an anthropomorphic striatal phantom: implications for the practice

Abstract

The aim of this study was to evaluate the effect of ordered subsets maximization expectation (OSEM) and filtered backprojection (FBP) reconstruction algorithms for the qualitative interpretation of DAT-SPECT. Data were acquired using an anthropomorphic striatal phantom and a gamma camera (SPECT/CT). Images were reconstructed using different values of the covariates applied in the OSEM and FBP algorithms (iteration, subsets, order, and cut-off frequency). Image quality was compared according to each set of covariates used in the reconstruction and extracted quantitative parameters of the image quality, such as C, CV RCR, and RSR, as well as the angular coefficients of the edges in regions of interest. Variations in the order from 0 to 10 do not influence the image if a trustworthy cut-off frequency range for FBP (0.9 to 1.6) and OSEM (1.2 to 1.5) are used. For OSEM, the iteration value and the number of subsets that guarantee better quality were those suggested by the developer of the algorithm used (3i8s). For a quality image, it is necessary to use the range of values found for the covariables order and cut-off frequency of the Butterworth filter in the FBP and OSEM reconstruction. OSEM reconstruction shows superiority in the images compared with FBP when the recommended three iterations and eight subsets are used. In the quantitative analyses, the evaluation showed that increasing the number of updates while allowing a better distinction of certain areas, culminates with a degradation image, making it inappropriate for clinical.