Follow-up Yttrium-90 Internal Pair Production PET/CT vs Brehmsstrahlung Imaging in Patients With Primary/Metastatic Liver Tumors

This is a prospective non-blinded case series involving the acquisition of a pair production PET/CT as soon as possible after an already performed Y-90 Sirspheres treatment of hepatic malignancy. It will be performed in addition to the standard Brehmsstrahlung SPECT scan. The sequence of the two scans in each case (PET/CT vs SPECT) will be determined by availability of the scanners at the time. However, it is intended that both be acquired on the day of the Y-90 treatment. The length of subject participation will be one year. The measures used will be mostly qualitative in nature, and will include: * Correlation with expected vs. achieved tumor coverage by the treatment * Correlation between treatment distribution depicted by Brehmsstrahlung scans vs. the Internal Pair Production PET/CT scans, to. * Detection of non-target embolization, where applicable, and qualitative comparison between the two modalities as to the conspicuity of the abnormality Qualitative methods will be used by the analysis of the obtained PET/CT images and comparing them to the Brehmsstrahlung SPECT images as previously described.