Deposition of Yttrium-90 microspheres (Y-90) in the gastroduodenum (GD) is associated with early stasis/reflux and likely caused by reflux to the gastroduodenal artery (GDA)

1162 Objectives Ulceration in GD after Y-90 therapy is caused by direct deposition of Y-90 in the mucosa. We studied the incidence of abnormal Y-90 deposition on post-infusion imaging and correlated it with parameters of infusion and clinical follow-up(FU) of 2 years. Methods A total of 153 Y-90 treatments were reviewed. Y-90 spheres were infused in the hepatic artery (Table), with intermittent infusion of contrast and arteriography. Post-infusion planar and SPECT/CT imaging of the abdomen were obtained using Y-90 bremsstrahlung. Results Early stasis or reflux during infusion, leading to partial delivery of intended Y-90 dose, was identified in 16 cases. The median of the percent delivered dose was 63% (range 27%-86%). Of these 16 cases, abnormal Y-90 activity in GD was identified in 6 cases(38%) with a median percent delivered dose of 59% (50-67%). These cases were treated prophylactically with proton inhibitor. 2 of the 6 cases showed marked Y-90 activity in GD and developed ulcers (1 also had pancreatitis) in FU, with confirmation of sphere deposition by pathology; the other 4 cases showed minimal to mild activity in GD and did not develop symptoms in FU. Other 137 cases received the full intended dose without encountering stasis/reflux. None of these 137 cases showed abnormal Y-90 activity, but 3 patients developed ulcers in FU. There was a significant difference in the frequency of cases showing abnormal Y-90 deposition between the groups with or without early stasis by χ2 test (p Conclusions Early stasis/reflux was identified as a major contributor to Y-90 deposition in the GD, likely due to reflux to the GDA