PET / CT mediastinal and liver FDG uptake: Effects of biological and procedural factors

To establish the effects of biological and procedural factors on mediastinal and liver [ 18 F ]‐fluorodeoxyglucose ( FDG ) uptake in oncological FDG positron emission tomography/computed tomography ( PET / CT ). Methods This retrospective study included 557 patients who had a baseline FDG PET / CT scan in 2008 and 2009. Mediastinal and liver standardised uptake values mean normalised to lean body mass ( SUV lbm mean) were measured in each patient. Univariate and multivariate regression models were established. Study population was then dichotomised into low and high body mass index ( BMI ) groups, and linear regression models were established for the effects of age, incubation period and blood glucose levels. Results BMI had the highest adjusted effect (standardised beta coefficient, b = 0.43) ( P  < 0.001) and partial correlation, adjusting for covariates included in the final model (r = 0.45; P  < 0.001) on mediastinal FDG uptake. Partial correlations (r) were 0.22 for age, −0.17 for male gender, −0.25 for incubation period and 0.14 for blood glucose ( P  < 0.001). The linear regression models showed significant differences in mediastinal FDG uptake between the low and high BMI groups and the effects of age, incubation period and basal blood glucose levels ( P  < 0.001). Similar results were observed for liver FDG uptake except the partial correlation for incubation period was r = −0.09 ( P  = 0.02). Conclusion BMI has the highest effect and correlation on mediastinal and liver FDG uptake. FDG uptake time has a greater effect on mediastinal than liver SUV lbm mean.