8:08 AM Abstract No. 60 - Fusion MAA-sulfur colloid spect imaging for Yttrium-90 radioembolization: towards customized physiology-based dose planning

Abstract

Purpose Yttrium-90 (90Y) radioembolization dose planning requires balancing caution against toxicity with aggressiveness for efficacy, but each is impossible to predict based solely on morphologic imaging. We investigate the use of fusion MAA-sulfur colloid SPECT imaging to provide physiologic information relevant to dose calculation and outcomes. Materials and Methods A dual SPECT protocol was used with IA injection of technetium-99m (99mTc)-MAA (1 mCi) as a predictor of subsequent 90Y distribution, followed by IV 99mTc-sulfur colloid (5 mCi) as a biomarker for normal hepatic tissue. The SPECT data were co-registered and fused. A voxel based method was used to predict the 90Y radiation absorbed dose to functional hepatic tissue by calculation of 99mTc-MAA activity in voxels with 99mTc-sulfur colloid uptake. Similarly, the absorbed dose to tumor was predicted by calculation of 99mTc-MAA activity in voxels without 99mTc-sulfur colloid. Response (mRECIST) was recorded at 3 months, laboratory data were collected at 2, 4 and 8 weeks, and patients were followed until death. Retrospective SPECT based dosimetry was correlated with parameters of toxicity and efficacy and compared with standard parameters of dosimetry, administered activity, and whole liver absorbed dose. Results A total of 56 patients were included (32 M, 24 F; median age 62; 27 HCC, 29 CRC, 32 resin, 24 glass microspheres, median activity 2.02 GBq, median whole liver dose 70 Gray). Toxicity parameters (serum bilirubin, AST, ALT, albumin, hemoglobin, and platelets) correlated significantly with SPECT-based functional liver absorbed dose (median 38 Gy, p Conclusion Fusion MAA-Sulfur colloid SPECT is useful to predict tumor and functional liver absorbed dose, which correlate with efficacy and toxicity, and may be used in the future to develop an individualized physiology-based dose-planning method.