2.2.2. Additional Single PET-Parameters

When evaluating single PET-parameters (mean/maximum standardized uptake value (SUVmean/max), Metabolic Tumor Volume (MTV) and Total Lesion Glycolysis (TLG)) additionally to mPERCIST classification according to peak standardized uptake value (SUVpeak) measurements, all responders (RECIST) showed a decline in all PET-parameters from baseline to the 3 month follow-up and from baseline to the 6 month follow-up, except SUVmean from baseline to the 6 month follow-up.

The mean changes of all PET-parameters over 6 months follow-up divided into DC/PD (RECIST) and significant differences between groups are shown in Table 1 and Figure 2. For both time-points, DC patients showed significantly lower SUVpeak (3 months: *p* = 0.004, 6 months: *p* = 0.023), SUVmax (3 months: *p* = 0.003, 6 months: *p* = 0.008), MTV (3 months: *p* = 0.010, 6 months: *p* = 0.006) and TLG values (3 months: *p* = 0.019, 6 months: *p* = 0.011). One patient was excluded due to not measurable uptake in baseline 18F-FDG-PET/CT. The percentage change of Tg-levels from baseline to the 3 month follow up and baseline to the 6 month follow-up 18F-FDG-PET/CT showed no significant difference between DC and PD patients (baseline to 3 months: −41% ± 72%, *p* = 0.853; baseline to 6 months: −45% ± 73%, *p* = 0.436).

**Table 1.** Mean changes and SD (%) of PET-parameters in patients with DC and PD according to RECIST from baseline to 3 and 6 month follow-up imaging.


DC, disease control; PD, progressive disease; SD, standard deviation; SUV, standard uptake value; MTV, metabolic tumor volume; TLG, total lesion glycolysis; \* *p*-value < 0.05; \*\* *p*-value < 0.01.

**Figure 2.** Mean changes of PET-parameters (**a**) SUVpeak, (**b**) SUVmean, (**c**) SUVmax, (**d**) MTV and (**e**) TLG in patients with DC and PD according to RECIST from baseline to 3 and 6 month follow-up imaging. 3M, 3 months; 6M, 6 months; DC, disease control; PD, progressive disease; SUV, standard uptake value; MTV, metabolic tumor volume; TLG, total lesion glycolysis.
