Aims: (1) To perform a comprehensive analysis of the time elapsed between the last G-CSF injection and the PET examination on the biodistribution of FDG, with emphasis on liver, spleen and bone marrow uptake; (2) To investigate whether an inversion of the liver to spleen ratio affects Deauville Scoring. Materials and methods: Retrospectively included were 74 consecutive diffuse large-B-cell lymphoma (DLBCL) patients referred for baseline and interim examinations and receiving immunochemotherapy with various G-CSF regimens. A comprehensive evaluation considering baseline MATV, factors affecting liver uptake, the type of G-CSF and the time elapsed between chemotherapy/G-CSF and interim PETs was performed. Results: Mean (±SD) percentage variation between baseline and interim pets (i-PET) for bone marrow (%Variation_BONE), liver (%Variation_LIVER) and spleen (%Variation_SPLEEN) were equal to 32.0(±46.9) %, 16.1(±42.8) % and 10.6(±51.1) %, respectively. %Variation_LIVER and %Variation_SPLEEN were higher in patients using lenograstim but this was linked to lower uptakes at baseline and was therefore likely not due to G-CSF itself. The mean delay between G-CSF injection and i-PET acquisition was not an independent explanatory variable for %Variation_BONE, %Variation_LIVER and %Variation_SPLEEN. On the contrary, %Variation_BONE and %Variation_SPLEEN were negatively correlated to the time-lapse between the end of chemotherapy and i-PET: ρ=-0.342 (p=0.010) and ρ=-0.529 (p<0.0001), respectively. Patients with a time-lapse since the last injection of chemotherapy < 17days displayed higher bone and spleen SUVmaxEARL. %Variation_LIVER was positively correlated to baseline MATV: ρ=0.243 (p=0.039). Patients displaying a high baseline MATV≥177cc had significantly lower liver SUVmaxEARL at baseline. This difference was no longer observed at i-PET, after tumours had shrunk. Conclusions: Neither the type of G-CSF used nor the time elapsed between its last injection and i-PET examination independently influences bone, hepatic or splenic uptakes at i-PET. The major determinant for the occurrence of a bone or spleen hypermetabolism on i-PET is the time elapsed between the chemotherapy and the examination, which should be maintained above 15 days. Inversion of the liver to spleen ratio appeared to be due to increased spleen hypermetabolism on i-PET, making unlikely an impact on Deauville scoring.