INCLUSION CRITERIA: High radiological suspicion of hepatocellular carcinoma (LR4 or LR5 based on the most current version of LI-RADS) with at least one measurable lesion on standard imaging modality (CT and/or MRI). Eligible for local ablative therapies (included but not limited to stereotactic radiation therapy, transarterial chem/radio/bland embolization, microwave ablation, radiofrequency ablation). Ability to take oral medication and be willing to adhere to the study intervention regimen. Age >=18 years. ECOG performance status <=2. Known human immunodeficiency virus (HIV)-infected individuals must be on effective anti-retroviral therapy with undetectable viral load within 6 months. Known chronic hepatitis B virus (HBV) infected individuals, must be on suppressive therapy with undetectable viral load. Individuals with a history of hepatitis C virus (HCV) infection must have been treated and cured. The effects of 18F-DCFPyL (study drug) on the developing human fetus are unknown. For this reason and because this agent as well as other therapeutic agents used in this trial are known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for 2 months after each study PET/CT imaging. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Ability of subject  EXCLUSION CRITERIA:  History of allergic reactions attributed to compounds of similar chemical or biologic composition to 18F-DCFPyL or other agents used in study. Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. Subjects with severe claustrophobia unresponsive to oral anxiolytics. Other medical conditions deemed by the principal investigator (or associates) to make the subject unsafe/ineligible for protocol procedures. Subjects weighing > 350 lbs (weight limit for scanner table), or unable to fit within the imaging gantry Serum creatinine > 2 times the upper limit of normal Pregnant women are excluded from this study because 18F-DCFPyL is an agent with the potential for teratogenic or abortifacient effects. as well as other agents used in this trial are known to be teratogenic.