Liver Tumor Enhancement at Hybrid Angio-CT and Comparison With Tumor and Hepatic Parenchymal Distribution of Yttrium-90 Microspheres by Positron Emission Tomography.

This single-center retrospective study evaluated patients who underwent treatment of a primary or secondary hepatic malignancy with injection of glass or resin yttrium-90 (Y) microspheres with a corresponding hybrid angiography-computed tomography (angio-CT) and Y positron emission tomography (PET). Volumetric contours were defined by three independent observers and were used to calculate relative tumoral enhancement at angio-CT. This parameter was compared with the tumor-to-normal (T/N) activity ratio predicted by technetium-99m macro-aggregated albumin (Tc-MAA) single photon emission computed tomography (SPECT) and microsphere activity distribution by Y PET. A similar correlation was observed for the enhancement ratio at angio-CT with observed microsphere distribution at Y PET (r=0.34) to that predicted by Tc-MAA SPECT (r=0.32). The enhancement ratio on angio-CT performed as well as Tc-MAA in the prediction of Y PET activity distribution. The technique could not be readily applied to tumors with large areas of hypoattenuation (necrosis) on angio-CT. With refinement and further study, this technique could be used as a quantitative adjunct to standard-of-care Tc-MAA SPECT for dosimetry calculations and prediction of microsphere distribution to maximize tumor response and minimize hepatotoxicity.