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

Introduction To establish the effects of biological and procedural factors on mediastinal and liver [¹⁸F]-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_lbmmean) 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 _lbmmean.