Accuracy of Prediction for Y-90 Glass Microsphere Radioembolization in Hepatocellular Carcinoma Using IntrahepaticTc-99m MAA planning SPECT/CT

1377 Objectives: Intrahepatic Tc-99m macro-aggregated (MAA) is usually used to determine the radiation dose to lungs and assess for abnormal abdominal shunting prior to Y-90 microsphere administration, which is a crucial step for radioembolization safety. MAA uptake can also be useful in predicting exact distribution and tumor dosimetry of radioembolization. Unlike Y-90 resin microsphere uptake which shows weak correlation with MAA (1), Y-90 glass microspheres (Y90 GM) are much less embolic and suitable for hepatocellular carcinoma (HCC) treatment, though its correlation with MAA is yet to be established. In this retrospective study, we correlated findings between MAA and Y-90 GM SPECT/CT images in patients with HCC both visually and semi-quantitatively. Methods: Consecutive 331 paired MAA/Y-90 GM SPECT/CT in 222 HCC patients were performed within 19±12 days between MAA and Y-90 scans. Hepatic segmental radioactivity distribution and number of lesions in the perfused part of liver were analyzed on MAA and Y-90 GM SPECT/CT scans. The distribution of radiotracer was categorized as concordant, minor discordant or major discordant between the two studies. Semi-quantitative analysis of tumor to perfused normal liver background ratio (TBR) using maximum and mean values was also performed. The effect of dissimilar/subselective Y90 GM small infusion area following MAA infusion of a larger liver portion as well as use of single versus multiple Y-90 GM doses on all variables were analyzed. Results: > MAA/Y90 GM SPECT/CT findings were predominantly concordant when hepatic lobar/sublobar infusion of MAA and Y90 GM were similar and considerably discordant in dissimilar Y90 GM/MAA infusions. The use of single versus multiple Y90 GM doses showed no significant differences in the concordance/discordance of both scans. There was excellent correlation between TBR on MAA and Y-90 GM SPECT/CT scans for both mean (p Conclusions: In planning Y90 GM radioembolization for HCC patients, the use of similar MAA hepatic arterial infusion can predict segmental distribution and number of lesions with high accuracy regardless of the number of Y90 treatment doses. Tumor count rates of MAA and Y90 GM SPECT/CT scans are considerably similar when MAA and Y90 GM infusions are planned in the same way, which may be useful in predicting Y-90 GM tumor radiation dosimetry.