Pair Production PET Imaging to Detect Particle Distribution in Patients Undergoing Yttrium-90 Radioembolization With Large Hepatocellular Carcinomas or Associated Portal Vein Thrombosis

The primary goal of the study is to see if the PET/CT will be able to determine the precise location of the Y-90 particles within the liver and within the tumors. We hope to use this information in order to see if these particles distribute evenly throughout large tumors or if the particles go into the tumor which is located in the portal vein.

The secondary goals are threefold. First correlate the distribution of Y90 particles (as demonstrated by PET/CT) with the degree of dead-tumor tissue. Second, see if there is a difference in the Y90 particle's distribution when a low particle load (1-3 million particles) is used compared to when a high particle load (6-8 million particles) is used. Lastly, compare the sensitivity of standard imaging ( bremsstrahlung imaging) currently being used for the Yttrium-90 angioembolization procedure to the sensitivity of the pair production PET research imaging.