Accuracy and Safety of Scout Dose Resin Yttrium-90 Microspheres for Radioembolization Therapy Treatment Planning: A Prospective Single-Arm Clinical Trial.

Purpose: To compare the accuracy and safety of 0.56 GBq resin yttrium-90 (Y) (scoutY) microspheres with those of technetium-99m macroaggregated albumin (MAA) in predicting the therapeutic Y (RxY) dose for patients with hepatocellular carcinoma (HCC).

Materials And Methods: This prospective single-arm clinical trial (Clinicaltrials.gov: NCT04172714) recruited patients with HCC. Patients underwent same-day mapping with MAA and scoutY. RxY activity was administered 3 days after mapping. Using paired t test and Pearson correlation, the tumor-to-normal ratio (TNR), lung shunt fraction (LSF), predicted mean tumor dose (TD), and nontumoral liver dose (NTLD) by MAA and scoutY were compared with those by RxY. Bland-Altman plots compared the level of agreement between the TNR and LSF of scoutY and MAA with that of RxY. The safety of scoutY was evaluated by examining the discrepancy in extrahepatic activity between MAA and scoutY.

Results: Thirty patients were treated using 19 segmental and 14 nonsegmental (ie, 2 contiguous segments or nonsegmental) therapies. MAA had weak LSF, moderate TNR, and moderate TD linear correlation with RxY. ScoutY had a moderate LSF, strong TNR, strong TD, and very strong NTLD in correlation with those of RxY. Furthermore, the TNR and LSF of scoutY had a stronger agreement with those of RxY than with those of MAA. In the nonsegmental subgroup, MAA had no significant correlation with the TD and NTLD of RxY, whereas scoutY had a very strong correlation with both of these factors. In the segmental subgroup, both MAA and scoutY had a strong linear correlation with the TD and NTLD of RxY.

Conclusions: Compared with MAA, scoutY is a more accurate surrogate for RxY biodistribution for nonsegmental therapies.