Estimation of Kinetic Parameters in Dynamic FDG PET Imaging Based on Shortened Protocols Using Simulated Annealing Method : A virtual clinical study

Abstract

Abstract Purpose: This study investigated the estimation of kinetic parameters and production of related parametric Ki images in FDG PET imaging using the proposed shortened protocol (three 3-min routine static images in 20-min, 60-min, and 90-min post injection) by means of the simulated annealing (SA) algorithm. Methods: Six realistic heterogeneous tumors and various levels of [18F] FDG uptake were simulated by XCAT phantom. An irreversible two-tissue compartment model (2TCM) using population-based input function (PBIF) was employed. The SA optimization algorithm was applied to estimate micro- and macro-parameters (K1, k2, k3, Ki). Results: A highly significant correlation (> 0.9) as well as limited bias (< 5%) were observed between kinetic parameters generated from two methods (two-tissue compartment full dynamic scan (2TCM-full) and two-tissue compartment by SA algorithm (2TCM-SA)). The analysis showed a strong correlation (> 0.8) between (2TCM-SA) Ki and SUV images. In addition, the tumor-to-background ratio (TBR) metric in the parametric (2TCM-SA) Ki images was significantly higher than SUV, although the SUV images provide better Contrast-to-noise ratio (CNR) relative to parametric (2TCM-SA) Ki images. Conclusions: Proposed shortened protocol by SA algorithm can estimate the kinetic parameters in FDG PET scan with high accuracy and robustness. It was also concluded that the parametric Ki images obtained from the 2TCM-SA as a complementary image of the SUV possess more quantification information than SUV images and can be used by the nuclear medicine specialist. This method has the potential to be an alternative to a full dynamic PET scan.