In the last years, radioembolization (RE) has emerged as a novel technique for the treatment of malignant hepatic lesions using (90)Y embedded in spheres, which are infused directly into the hepatic arterial circulation. (90)Y-spheres, once implanted in liver, can release a significant radiation burden to neoplastic cells with a relative low dose to normal parenchyma. (90)Y RE results as a combination of embolization and
radiation therapy, thus the standard radiologic follow up modalities may be not sufficiently accurate to assess
tumor response to treatment. (18)Fluoro-deoxyglucose Positron Emission Tomography ((18)F-FDG PET) detects
glucose uptake and metabolic activity in
tumor cells. (18)F-FDG PET has become a well established diagnostic tool in many oncological scenarios. Furthermore, PET response criteria (PERCIST) have been recently introduced to categorize the metabolic response to
therapy of
cancer patients. Several semiquantitative parameters, such as SUVmax and its changes, the Functional
Tumor Volume and the Total Lesion Glycolysis can be useful to accurately assess
tumor changes after
therapy. The purpose of this article is to present the literature on the role of (18)F-FDG PET in the evaluation of patients with primary and secondary liver
tumors treated with (90)Y RE.