Objectives: The aim of the study was to evaluate the role of F-fluorodeoxyglucose PET computed tomography (F-FDG PET CT) as an independent prognostic indicator in patients with hepatocellular carcinoma (HCC).
Materials and methods: PET contrast-enhanced CT scans of 100 consecutive patients with HCC were reviewed retrospectively. Patients were asked to fast for 6 h before the study and blood glucose levels were monitored and ensured to be less than 200 mg/dl before injection of F-FDG. After administering the F-FDG injection (370-550 MBq) patients were instructed to rest comfortably for 45-60 min. All images were acquired using a dedicated GE Discovery PET/CT scanner. The PET CT scans of all the patients were reported separately by two nuclear medicine physicians. A stage-wise analysis of the compiled data was carried out. Lesions that showed standardized uptake values greater than background activity (activity in adjacent normal liver tissue) were defined as having increased F-FDG uptake. Pearson's χ -test or the Kruskal-Wallis test was used to assess statistical significance. A P value less than 0.05 was taken as significant.
Results: In this retrospective study of 100 HCC patients, a radiologically higher-stage disease was found more commonly in patients with F-FDG-avid primary tumors (P<0.001), whereas a lower-stage disease was found in patients with non-F-FDG-avid primary tumors. The non-F-FDG-avid tumors also showed lower incidence of metastatic disease and portal vein thrombosis (P<0.001). The histopathological findings of the patients who underwent liver transplantation demonstrated that a higher-grade tumor was more common in the F-FDG-avid tumor group than in the non-F-FDG-avid tumor group (P<0.05).
Conclusion: An F-FDG PET CT scan can be used not only for staging but also as a tool for preoperative prediction of cellular differentiation in patients with HCC. The F-FDG uptake seen on a PET scan can serve as a molecular signature for management decisions and can be used as an independent and significant prognostic factor in patients with HCC.