Variability of hepatic 18-FDG uptake at interim PET in Hodgkin lymphoma patients

Objectives When evaluating response of Hodgkin lymphoma (HL) to chemotherapy on interim 18FDG-PET/CT, physiological liver uptake is used as reference. HL sites with uptake > liver means positive study. We aimed at examining factors that might influence liver uptake as reference organ.

Methods Fifty patients with Hodgkin lymphoma who received baseline 18FDG-PET/CT (PET1) and interim PET (PET2; usually after 2 cycles of ABVD chemotherapy) were included retrospectively. SUV mean normalized for body weight (SUVmean) and for lean body mass (SULmean) were obtained from 2-dimensional regions of interest (ROI) in the right lobe of the liver.

Results On univariate analysis, liver SUVmean values on interim PET increased with increasing body-mass index “BMI” (p=0.0453), and were higher in women (p=0.0401). These factors remained significant on multivariate analysis (respectively p=0.009 and p=0.008). No significant correlation was found with delay post-injection, blood glucose level and age. Liver SULmean values were not affected by the studied variables. Average liver SUVmean values in the 50 patients were similar at baseline and interim PET. In 11 patients (22%), however, there was ≥ 30% variation in liver SUVmean between PET1 and PET2. No factors explaining intrapatient variation in hepatic uptake between PET1 and PET2 were found on correlation analysis.

Conclusions At interim PET in HL patients, liver SUVmean depends on BMI and gender, but not liver SULmean. Furthermore, our study conducted with standard clinical procedure also confirmed the high range of liver uptake values from one patient to another. Caution is required when using liver SUV as reference in patients with high BMI. Intrapatient fluctuation in liver SUVmean should also be expected.

Research Support None