Preclinical dynamic ¹⁸F-FDG PET – tumor characterization and radiotherapy response assessment by kinetic compartment analysis

Figures & data

Figure 1. ¹⁸F-FDG uptake in one animal's heart at different time points (A). The resulting AIF determined by fitting a biexponential function to the mean TAC of the identified 3D region of the heart (B).

Figure 2. Mean and SEM TACs of eight untreated tumors and eight irradiated tumors, corrected for differences in injected dose of ¹⁸F-FDG by normalizing the tumor TACs by the area under the AIF. Differences between the two groups were significant in the initial uptake phase (t=1 min, p=0.029; t=1 min 15 s, p=0.001; t=1 min 30 s, p=0.014) and at the end of the dynamic scan (t=27.5 min, p=0.029; t=35 min, p=0.009; t=45 min, p=0.009; t=55 min, p=0.009).

Figure 3. Tumor regions with high and low uptake of ¹⁸F-FDG (A). Different TAC was detected in the high uptake region (B) and the low uptake region (C), including different free and bound components. The kinetic parameters of the high uptake region were k₁=0.189 min⁻¹, k₂=0.616 min⁻¹, and k₃=0.072 min⁻¹, whereas in the low uptake region the parameters were k₁=0.098 min⁻¹, k₂=0.425 min⁻¹, and k₃=0.048 min⁻¹.

Figure 4. Parametrical maps of k₁, k₂,k₃ and r² extracted from the kinetic analysis of dynamic ¹⁸F-FDG PET. Six slices of an irradiated CWR22 xenograft are shown, together with the tumor's corresponding median and range values for each parameter (in units of min⁻¹ for k₁, k₂ and k₃).

Figure 5. Homogeneous intra-group median values of the k₁ (min⁻¹) (A), k₂ (min⁻¹) (B) and k₃ (min⁻¹) (C) parameters in the untreated xenografts (black), whereas k₁ (p=0.028), k₂ (p=0.010) and k₃ (p=0.028) values changed significantly after irradiation (white).