Prone position PET/CT is useful in reducing gravity-dependent opacity-related [18F]fluorodeoxyglucose uptake

ObjectivesThis study aimed to investigate whether performing [F-18]fluorodeoxyglucose ([F-18]FDG) positron emission tomography/computed tomography (PET/CT) in the prone position could reduce [F-18]FDG uptake in dependent lungs.MethodsPatients who underwent [F-18]FDG PET/CT in both supine and prone positions from October 2018 to September 2021 were reviewed retrospectively. [F-18]FDG uptake of dependent and nondependent lungs was analysed visually and semi-quantitatively. A linear regression analysis was performed to examine the association between the mean standardised uptake value (SUVmean) and the Hounsfield unit (HU).ResultsA total of 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 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). Linear regression analysis revealed a strong association between the SUVmean and HU in sPET/CT (R = 0.86, p < 0.001) and moderate association in pPET/CT (R = 0.65, p < 0.001). One hundred and fifteen patients (85.2%) had visually discernible [F-18]FDG uptake in the posterior lung on sPET/CT, which disappeared on pPET/CT in all but one patient (0.7%, p < 0.001).Conclusions[F-18]FDG uptake of the lung had moderate-to-strong associations with HU. Gravity-dependent opacity-related [F-18]FDG uptake can be effectively reduced on prone position PET/CT.

Automated summary

This study aimed to investigate the reduction of [F-18]FDG uptake in dependent lungs by performing [F-18]FDG PET/CT in the prone position. The results showed that dependent lungs had significantly higher SUVmean and HU compared to nondependent lungs on both supine and prone position PET/CT. The study concluded that prone position PET/CT can effectively reduce gravity-dependent opacity-related [F-18]FDG uptake.