Objective:To evaluate the kinetic metrics changes of FDG in key organs after chemo-immunotherapy in patients with locally advanced non-small cell lung cancer (NSCLC) identified by total-body PET/CT dynamic imaging, and explore its potential biological significance.Methods:From August 2020 to March 2021, 16 patients (13 males, 3 females; age: 43-67 years) with locally advanced NSCLC who underwent total-body 18F-FDG PET/CT dynamic imaging in Sun Yat-sen University Cancer Center were retrospectively analyzed. ROIs of key organs were drawn at baseline and after chemo-immunotherapy to obtain the time-activity curves (TACs). The kinetic metrics, including K1, k2, k3 and metabolic rate of FDG (MR FDG), were fitted by the two-tissue compartment model. Paired t test or Wilcoxon signed rank test was used to compare the differences of FDG kinetic parameters in each organ before and after treatment. Results:Compared with baseline, SUV max of colon (3.23±1.29 vs 4.81±2.73), MR FDG ((2.77±1.96) vs 3.56(1.07, 9.89) μmol·100 g -1·min -1) of lungs, SUV max (2.16±0.27 vs 2.33±0.41), k3 ((0.008±0.002) vs (0.012±0.004) min -1) and MR FDG ((2.65±0.81) vs (3.76±1.59) μmol·100 g -1·min -1) of spleen, and SUV max (2.59±0.45 vs 4.49±2.73), k2 ((0.76±0.37) vs (1.27±0.66) min -1), k3 ((0.032±0.007) vs (0.066±0.029) min -1) and MR FDG ((5.14±1.44) vs (8.39±2.67) μmol·100 g -1·min -1) of bone marrow were increased after chemo-immunotherapy with significant differences ( t values: from -5.40 to 3.47, z=-2.02, all P<0.05). There were no significant differences of SUV max, k values and MR FDG in other organs ( t values: from -2.00 to 2.35, z values: from -1.45 to -0.05, all P>0.05). Conclusions:After chemo-immunotherapy, the activation of immune system may be manifested as the increase of FDG kinetic rate constants in spleen and bone marrow. The lung and colon may be target organs for immune-related adverse effects.