The role of (18)F-FDG positron emission tomography in the follow-up of liver tumors treated with (90)Yttrium radioembolization

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.