PMC8321507_01
Previous (a) and current (b-l) [18F]FDG PET/CT of an asymptomatic 80-year-old man with a history of non-Hodgkin lymphoma. Maximum intensity projection (a-b), transaxial fused PET/CT (c, e, g, i), and CT (d, f, h, l) images of [18F]FDG uptake in the lungs
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PMC8321507_01_42399_2021_1030_Fig1_HTML.jpg
Fig1
Compared with the previous PET/CT scan (Fig. 1a), the current PET/CT (Fig. 1b) showed resolution of mediastinal lymph node uptake (black arrow). However, PET/CT and CT images (Fig. 1c-l) revealed the appearance of multiple bilateral FDG-avid ground-glass opacities (GGOs, yellow arrows), with a predominantly peripheral distribution in the posterior segments of the inferior lung lobes. Moreover, new mildly increased uptake was seen in several mediastinal lymph nodes, without enlargement on CT images (Fig. 1b, red arrow). 
PMC8321507_02
Previous (a) and current (b-l) [18F]FDG PET/CT of an asymptomatic 51-year-old man with a history of oral cavity squamous cell carcinoma. Maximum intensity projection (a-b), transaxial and coronal fused PET/CT (c, e, g), and CT (d, f, h) images of [18F]FDG uptake in the lungs
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PMC8321507_02_42399_2021_1030_Fig2_HTML.jpg
Fig2
Follow-up PET/CT (Fig. 2b) showed a good partial metabolic response of the primary tumor (black arrows) compared with the baseline scan (Fig. 2a). However, PET/CT showed the appearance of few bilateral GGOs (yellow arrows) in the posterior segments of the inferior lung lobes (Fig. 2 c-h) associated with hilar and mediastinal lymph nodes (Fig. 2b, red arrow), both mildly FDG-avid. 