Hepatic Metabolism of Galactose and the Galactose Analog FDGal in Patients With Liver Disease and Healthy Subjects

The elimination of the carbohydrate galactose is used in daily clinical work with liver patients as a quantitative measure of metabolic liver function, as the liver test "The Galactose Elimination Capacity", GEC. We are working to develop a PET/CT scanning procedure for providing 3D images of the hepatic galactose elimination and measurement of regional values. This may be used for example for planning resection or stereotactic radiotherapy of a patient with malignant tumor in the liver. Will the patient be able to tolerate removal of the necessary part of the liver? We will include 10 patients with liver cirrhosis and 6 healthy human subjects. Direct measurements of the hepatic galactose elimination (successive constant iv infusions of galactose in increasing doses with measurements of blood concentrations of galactose in blood from an artery and a liver vein, and measurements of liver blood flow by indocyanine green, Ficks principle) are compared with PET/CT measurements after iv injection of a 18F-labelled galactose analog, FDGal. Based on previous studies in pigs, we perform detailed calculations of the hepatic galactose elimination kinetics by the two methods, including estimation of a factor ("lumped constant") for recalculating PET/CT data to data for natural galactose. Besides possible practical clinical importance, the project elucidates basic problems concerning liver metabolism using PET.