Reconstruction of dynamic pet images using accurate system point spread function modeling: Effects on parametric images

Quantitative analysis of positron emission tomography (PET) dynamic images allows to estimate physiological parameters such as glucose metabolic rate (GMR), perfusion, and cardiac output (CO). However, several physical effects such as photon attenuation, scatter and partial volume can reduce the accuracy of parameter estimation. The main goal of this work was to improve small animal PET image quality by introducing system point spread function (PSF) in the reconstruction scheme and to evaluate the effect of partial volume correction (PVC) on physiological parameter estimation. Images reconstructed respectively using constant and spatially variant (SV) PSFs and no PSF modeling was compared. The proposed algorithms were tested on simulated and real phantoms and mice images. Results show that the SV-PSF-based reconstruction method provides a significant contrast improvement of small animals PET cardiac images and, thus, the effects of PVC on physiological parameters were evaluated using such algorithm. Simulations show that the proposed PVC method reduces errors with respect to the true values for parametric images of GMR and perfusion. A reduction of CO percentage error with respect to the original value was also obtained using the SF-PSF approach. In conclusion, SV-PSF reconstruction method provides a more accurate estimation of several physiological parameters obtained from a dynamic PET scan.