2-[¹⁸F]fluoro-2-deoxy-D-galactose PET/CT of hepatocellular carcinoma is not improved by co-administration of galactose

Introduction: PET with [¹⁸F]fluoro-2-deoxy-D-galactose (¹⁸F-FDGal) is a promising imaging modality for detection of hepatocellular carcinoma (HCC). However, it can be difficult to distinguish small intrahepatic HCC lesions from surrounding liver tissue. Ut the competitive inhibition that galactose shows towards hepatic ¹⁸F-FDGal metabolism, we tested the hypothesis that co-administration of galactose, at near-saturating doses, inhibits ¹⁸F-FDGal metabolism to a greater extent in non-malignant hepatocytes than in HCC cells. This would increase the tumor to background ratio in the ¹⁸F-FDGal PET scans with co-administration of galactose. Methods: Three patients known to have HCC underwent two ¹⁸F-FDGal PET/CT scans on consecutive days, one with and one without simultaneous constant intravenous infusion of galactose. On both days, ¹⁸F-FDGal was injected in the beginning of a 45-min dynamic PET scan of the liver followed by a static PET scan from mid-thigh to the top of the skull starting 60–70 min after ¹⁸F-FDGal administration. Parametric images of the hepatic metabolic function expressed in terms of hepatic systemic clearance of ¹⁸F-FDGal were generated from the dynamic PET recordings. Results: Co-administration of galactose did not give significantly better discrimination of the HCC lesions from background. Parametric images of the hepatic metabolic function did not add additional useful information to the detection of HCC lesions compared to the static images of radioactivity concentrations. Conclusion: Co-administration of galactose did not improve the interpretation of the ¹⁸F-FDGal PET/CT images and did not improve the detection of intrahepatic HCC lesions, either using static or parametric images.