Quantitative FDG-PET/CT assessment of alterations in global hepatic metabolism due to cirrhosis

Objectives To quantify alterations in global hepatic metabolic activity due to cirrhosis through FDG-PET/CT.

Methods Thirty three subjects were included in this retrospective study. Group 1 (n=11) had no malignancy or cirrhosis, group 2 (n=10) had extrahepatic malignancy but no cirrhosis, and group 3 (n=12) had extrahepatic malignancy and cirrhosis. Subjects with malignancy did not receive chemotherapy or radiation therapy within 6 months prior to FDG-PET/CT. 2D ROIs were drawn around the liver on each transaxial slice passing through the liver, and SUVmean and ROI area from each slice were recorded. Average hepatic SUVmean was calculated as the average of SUVmean from all ROIs in each subject. The products [ROI area × slice thickness] and [ROI area × slice thickness × ROI SUVmean] were calculated for each slice and summed over to generate hepatic volume (HV) and mean hepatic metabolic-volumetric-product (HMVPmean). Unpaired t-testing was used to compare average hepatic SUVmean, HV, and HMVP between groups.

Results Subjects with cirrhosis (group 3) had significantly lower hepatic SUVmean (1.55±0.29) and HMVP (2238.29±903.60cc) (p<0.05) compared to those of group 1 and 2. Average SUVmean in groups 1 and 2 were 1.85±0.19 and 1.77±0.26, respectively (p=0.42), and average HMVP in groups 1 and 2 were 2928.87±654.31cc and 3025.04±1023.09cc, respectively (p=0.12). There was no significant difference in HV between the 3 groups.

Conclusions Through quantitative assessment of the liver on FDG-PET/CT, we have demonstrated that global hepatic metabolic activity is significantly decreased in the cirrhotic liver compared to the non-cirrhotic liver, which is probably related to a combination of decreased hepatocyte function and increased hepatic fibrosis. This approach may be useful to assess global hepatic function in patients with cirrhosis and other conditions