Comparison of dosimetry results obtained from pre-treatment tc-99m MAA spect/ct imaging and post-treatment PET/CT or PET/CT and SPECT/CT imaging in patients undergoing intrahepatic transarterial Y-90 microsphere radioembolization therapy

Aim: The agreement between multi-compartment and voxel-based dosimetry results obtained from Tc-99 MAA performed for simulation purposes before TARE treatment and Y-90 SPECT and Y-90 PET images after treatment was investigated. Material and Method: 51 patients who received TARE treatment were retrospectively examined and dosimetric analyses were performed with Tc-99m MAA SPECT/CT, Y-90 SPECT/CT, and Y-90 PET/CT or PET/MR images. The relationship between TDmean, PNTDmean, and WLNTDmean obtained by multi-compartment dosimetry and tumoral DVolume and HI values obtained by voxel-based dosimetry from all three modalities were examined. Results: The agreement between TDmean measurements and Tc-99m MAA and Y-90 PET was good, while the agreement between Tc-99m MAA and Y-90 SPECT was found to be moderate. PNTDmean and WLNTDmean measurements showed good agreement between the three images. In voxel-based dosimetry, the highest agreement between the three images was observed between D50 and D70. The HI value showed a significant difference between the methods, and it was observed that the heterogeneity was more pronounced in Y-90 PET than in other images. There was no significant difference in HI values between the glass and resin microsphere groups. Conclusion: Multi-compartment dosimetry results measured with pre-treatment Tc-99m MAA and post-treatment Y-90 SPECT and PET showed moderate-good agreement. Although Tc-99m MAA is not ideal in terms of treatment planning, it is an adequate radiopharmaceutical. While Y-90 PET seems more successful in post-treatment dosimetry, Y-90 SPECT is also sufficient in terms of clinical benefit. D50, D70 and HI values obtained with voxel-based dosimetry show the potential to contribute to the clinical approach.