Altered hepatic metabolic activity in patients with hepatic steatosis on FDG PET/CT

FDG PET studies frequently use the liver as an internal reference organ to assess the significance of FDG uptake in pathologic processes involving other organs. The purpose of this study was to assess whether hepatic steatosis has a significant effect on the standardized uptake value (SUV) of the liver.

This prospective case-control study analyzed FDG PET/CT scans of patients with frank hepatic steatosis on the unenhanced CT portion of the study. Maximum SUVs (corrected for both body weight [SUV(bw)] and lean body mass [SUV(lbm)]) in 37 patients with hepatic steatosis were compared with those in 37 control patients without hepatic steatosis.

Patients with hepatic steatosis had statistically significant smaller mean (± SD) values than did the control subjects for liver SUV(lbm) (1.91 ± 0.57 vs 2.17 ± 0.36), liver SUV(lbm)-mediastinum ratio (1.23 ± 0.19 vs 1.35 ± 0.19), and liver SUV(bw)-mediastinum ratio (1.24 ± 0.16 vs 1.39 ± 0.22).

Hepatic steatosis results in a small statistically significant decrease in hepatic metabolic activity, as measured by FDG PET. However, because the degree of change is small, compared with healthy control subjects, this decrease is unlikely to have any clinical significance on the use of the liver as an internal reference organ.