PET/CT > Normal Activity > Abdomen and Pelvis > Liver

Liver

Normal liver

 

The liver usually demonstrates greater activity than background bloodpool activity. The distribution of liver activity is typically heterogeneous, making it difficult to detect focal parenchymal abnormalities especially small ones. This problem is further compounded by artifacts which result from attenuation correction methods. The liver is a major organ for carbohydrate metabolism and storage. Specifically, it is involved in glycolysis and glycogen storage. Hepatocytes have high levels of glucose-6-phosphatase which results in enhanced dephosphorylation of FDG-6-phosphate and accelerated clearance of intracellular FDG from the liver compared to other organs. Primary liver tumors also have high levels of glucose-6-phosphatase and therefore demonstrate relatively rapid clearance of FDG compared to other tumors. Therefore, hepatic tumors might not be discernable from adjacent normal parenchyma due to similar levels of FDG at the time of imaging. Any activity which is clearly more focal and more intense than other activity in the liver should be considered suspicious and a search for evidence of a parenchymal abnormality on the CT images should be performed. Correlation with a dedicated enhanced liver mass protocol CT or MRI would likely also be necessary in the work-up of a focus of abnormal activity concerning for malignancy.