We investigated the role of [18F]FDG positron emission tomography/computed tomography (PET/CT) in evaluating ground-glass nodules (GGNs) by visual analysis and tissue fraction correction. A total of 40 pathologically confirmed ≥1 cm GGNs were evaluated visually and semiquantitatively. [18F]FDG uptake of GGN distinct from background lung activity was considered positive in visual analysis. In semiquantitative analysis, we performed tissue fraction correction for the maximum standardized uptake value (SUVmax) of GGN. Of the 40 GGNs, 25 (63%) were adenocarcinomas, 9 (23%) were minimally invasive adenocarcinomas (MIAs), and 6 (15%) were adenocarcinomas in situ (AIS). On visual analysis, adenocarcinoma showed the highest positivity rate among the three pathological groups (88%, 44%, and 17%, respectively). Both SUVmax and tissue-fraction–corrected SUVmax (SUVmaxTF) were in the order of adenocarcinoma > MIA > AIS (p = 0.033 and 0.018, respectively). SUVmaxTF was significantly higher than SUVmax before correction (2.4 [1.9–3.0] vs. 1.3 [0.8–1.8], p < 0.001). When using a cutoff value of 2.5, the positivity rate of GGNs was significantly higher in SUVmaxTF than in SUVmax (50% vs. 5%, p < 0.001). The diagnostic sensitivity of [18F]FDG PET/CT in predicting the malignancy of lung GGN was improved by tissue fraction correction and visual analysis.

Purpose We investigated whether [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) taken in the prone position could reduce [18F]FDG uptake in dependent lungs. Methods Patients who underwent [18F]FDG PET/CT in both supine and prone positions from October 2018 to September 2021 were reviewed retrospectively. [18F]FDG uptake of dependent and nondependent lungs was analysed visually and semi-quantitatively. A linear regression analysis was also performed to examine the association between the mean standardised uptake value (SUVmean) and the Hounsfield unit (HU). Results Totally, 135 patients (median age, 66 years [interquartile range: 58–75 years]; 80 men) were included. Dependent lungs showed significantly higher SUVmean and HU than nondependent lungs on both supine position PET/CT (sPET/CT, 0.59 ± 0.14 vs. 0.36 ± 0.09, p < 0.001; −671 ± 66 vs. −802 ± 43, p < 0.001; respectively) and prone position PET/CT (pPET/CT, 0.45 ± 0.12 vs. 0.42 ± 0.08, p < 0.001; −731 ± 67 vs. −790 ± 40, p < 0.001; respectively). In the linear regression analysis, there was a strong association between the SUVmean and HU in sPET/CT (R = 0.86, p < 0.001) and a moderate association in pPET/CT (R = 0.65, p < 0.001). One hundred and fifteen patients (85.2%) had visually discernible [18F]FDG uptake in the posterior lung on sPET/CT, which disappeared on pPET/CT in all but one patient (0.7%, p < 0.001). Conclusion [18F]FDG uptake of the lung had moderate-to-strong associations with HU. Gravity-dependent opacity-related [18F]FDG uptake can be effectively reduced on prone position PET/CT.

Purpose: We investigated the role of [18F]-FDG positron-emission tomography/computed tomography (PET/CT) in evaluating ground-glass nodules (GGNs) by visual analysis and tissue fraction correction.Methods: A total of 40 pathologically confirmed ≥1-cm GGNs were evaluated visually and semi-quantitatively. [18F]-FDG uptake of GGN distinct from background lung activity was considered positive in visual analysis. In semi-quantitative analysis, we performed tissue fraction correction for the maximum standardised uptake value (SUVmax) of GGN.Results: Of 40 GGNs, 25 (62.5%) were adenocarcinomas, 9 (22.5%) were minimally invasive adenocarcinomas (MIAs), and 6 (15%) were adenocarcinomas in situ (AIS). On visual analysis, adenocarcinoma showed the highest positivity rate among the three pathology groups (88.0%, 44.4%, 16.7%, respectively). Both SUVmax and tissue fraction corrected SUVmax (SUVmaxTF) were in order of adenocarcinoma > MIA > AIS (p = 0.033 and 0.018, respectively). SUVmaxTF was significantly higher than SUVmax before correction (2.4 [1.9–3.0] vs. 1.3 [0.8–1.8], p < 0.001). When using a cut-off value of 2.5, the positivity rate of GGNs was significantly higher in SUVmaxTF than in SUVmax (50.0% vs. 5.0%, p < 0.001).Conclusions: Tissue fraction correction and visual analysis increased the diagnostic sensitivity of [18F]-FDG PET/CT in predicting malignancy of lung GGN.

We investigated whether [ 18 F] uorodeoxyglucose ([ 18 F]FDG) positron emission tomography/computed tomography (PET/CT) taken in the prone position could reduce [ 18 F]FDG uptake in dependent lungs. MethodsPatients who underwent [ 18 F]FDG PET/CT in both supine and prone positions from October 2018 to September 2021 were reviewed retrospectively. [ 18 F]FDG uptake of dependent and nondependent lungs Conclusion [ 18 F]FDG uptake of the lung had moderate-to-strong associations with HU. Gravity-dependent opacityrelated [ 18 F]FDG uptake can be effectively reduced on prone position PET/CT.