PET coupled with computed tomography (CT) is indicated for the management of patients undergoing selective internal radiation therapy (SIRT), both as an aid to treatment planning as well as for post-SIRT dosimetry and the assessment of the metabolic response. PET-CT plays an important role in not only identifying the target tumor volume, but also for the prognostic stratification of patients and the exclusion of those with significant metabolic activity in extrahepatic lesions that cannot be controlled with radiotherapy and/or systemic chemotherapy.