4:12 PM Abstract No. 129 Intrahepatic flow redistribution prior to segmental Yttrium-90 radioembolization for challenging tumor vasculature

Abstract

Hepatic tumors with complex vascular supply, inaccessible feeding vessels, and/or poor tumor perfusion are prone to transarterial treatment failure. This concern is compounded in the setting of Yttrium-90 (Y90) radioembolization (RE), which is often non-embolic, flow-dependent, and relies on high threshold radiation dose for response. We describe our experience with intrahepatic flow redistribution using bland or coil embolization prior to RE of tumors with challenging vascular supply. Between 4/2014-7/2017, 19 patients (14 male, median age 62) with focal hepatocellular carcinoma underwent embolization for the purpose of intrahepatic flow redistribution during RE mapping or treatment. Hepatic redistribution (HR) was performed by embolization of vessels supplying normal hepatic parenchyma in cases when flow was not preferential to target tumor. Tumor-specific redistribution (TR) was performed by embolization of accessory feeding vessel(s) supplying the lesion, but not amenable to subselective RE. Lesion characteristics, vascular supply, treatment approach, angiography, and adverse events (AEs) were reviewed. Dosimetry coverage based on mTc-MAA and Y90 SPECT-CT was evaluated against pretreatment CT or MRI. Radiographic response was assessed by mRECIST. 13 cases of HR and 6 cases of TR were identified. Embolization was performed at the segmental (n = 4) or subsegmental level (n = 14), and at the gastroduodenal artery (n = 1). Fourteen right and 5 left-sided HCCs were treated (mean size 3.7 ± 2.1 cm). Embolic material included: calibrated microspheres (n = 12, range 40-500 μm), detachable microcoils (n = 7), and Gelfoam (n = 1). There were no procedure-related AEs. Post-treatment SPECT-CT dosimetry coverage was concordant with target lesions in all cases. Mean follow-up was 7.2 ± 6.7 months. Tumor-specific response was 68% complete response, 11% partial response, 5% stable disease, and 16% progressive disease by mRECIST. No major adverse events or grade 3/4 hepatotoxicity occurred up to 30 days. Intrahepatic flow redistribution prior to RE is safe with 79% objective response in the setting of complex vascular supply or poor relative tumor perfusion.