## Abstract

In quantitative dynamic PET studies, graphical analysis methods including the Gjedde-Patlak plot, the Logan plot, and the relative equilibrium-based graphical plot (RE plot) (Zhou Y., Ye W., Brašić J.R., Crabb A.H., Hilton J., Wong D.F. 2009b. A consistent and efficient graphical analysis method to improve the quantification of reversible tracer binding in radioligand receptor dynamic PET studies. Neuroimage 44(3):661-670) are based on the theory of a compartmental model with assumptions on tissue tracer kinetics. If those assumptions are violated, then the resulting estimates may be biased. In this study, a multi-graphical analysis method was developed to characterize the non-relative equilibrium effects on the estimates of total distribution volume (DV_{T}) from the RE plot. A novel bi-graphical analysis method using the RE plot with the Gjedde-Patlak plot (RE-GP plots) was proposed to estimate DV_{T} for the quantification of reversible tracer kinetics that may not be at relative equilibrium states during PET study period. The RE-GP plots and the Logan plot were evaluated by 19 [^{11}C]WIN35,428 and 10 [^{11}C]MDL100,907 normal human dynamic PET studies with brain tissue tracer kinetics measured at both region of interest (ROI) and pixel levels. A 2-tissue compartment model (2TCM) was used to fit ROI time activity curves (TACs). By applying multi-graphical plots to the 2TCM fitted ROI TACs which were considered as the noise-free tracer kinetics, the estimates of DV_{T} from the RE-GP plots, the Logan plot, and the 2TCM fitting were equal to each other. For the measured ROI TACs, there was no significant difference between the estimates of the DV_{T} from the RE-GP plots and those from 2TCM fitting (p = 0.77), but the estimates of the DV_{T} from the Logan plot were significantly (p < 0.001) lower, 2.3% on average, than those from 2TCM fitting. There was a highly linear correlation between the ROI DV_{T} from the parametric images (Y) and those from the ROI kinetics (X) by using the RE-GP plots (Y = 1.01X + 0.23, R^{2} = 0.99). For the Logan plot, the ROI estimates from the parametric images were 13% to 83% lower than those from ROI kinetics. The computational time for generating parametric images was reduced by 69% on average by the RE-GP plots in contrast to the Logan plot. In conclusion, the bi-graphical analysis method using the RE-GP plots was a reliable, robust and computationally efficient kinetic modeling approach to improve the quantification of dynamic PET.

Original language | English |
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Pages (from-to) | 2947-2957 |

Number of pages | 11 |

Journal | NeuroImage |

Volume | 49 |

Issue number | 4 |

DOIs | |

State | Published - Feb 15 2010 |

## Keywords

- Gjedde-Patlak plot
- Logan plot
- PET
- RE plot
- Relative equilibrium