Variability of Hepatic 18F-FDG Uptake at Interim PET in Patients With Hodgkin Lymphoma.

Abstract

When evaluating response of Hodgkin lymphoma (HL) to chemotherapy on interim (18)F-FDG-PET/CT, physiological liver uptake is used as reference. Hodgkin lymphoma sites with uptake greater than liver are interpreted as positive. We aimed at examining factors that might influence liver uptake as reference organ. Fifty patients with HL who received baseline (18)F-FDG-PET/CT (PET1) and interim PET (PET2), usually after 2 cycles of adriamycin bleomycin, vinblastine, and dacarbazine chemotherapy, were included retrospectively. SUVmean normalized for body weight (SUVmean) and for lean body mass (SULmean) were obtained from regions of interest in the right lobe of the liver. On univariate analysis, liver SUVmean 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 (P = 0.009 and P = 0.008, respectively). No significant correlation was found with postinjection delay, blood glucose level, and age. Liver SULmean were not affected by the studied variables. Average liver SUVmean in the 50 patients were similar at baseline and interim PET. In 11 patients (22%), however, there was 30% or greater 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. At interim PET in patients with HL, liver SUVmean depends on BMI and sex, 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.