Safety and Efficacy Assessment of Flow Redistribution by Occlusion of Intrahepatic Vessels Prior to Radioembolization in the Treatment of Liver Tumors

We evaluated the feasibility, safety, and efficacy of radioembolization (administered from one or two vascular points) after the redistribution of arterial blood flow in the liver in patients with hepatic neoplasms and arterial anatomic peculiarities (AAP). Twenty-four patients with liver neoplasms and AAP (graded according to Michel’s classification) were included in the study. During pretreatment angiographic planning, all extrahepatic vessels that could feed the tumor were embolized and the intrahepatic vessels occluded in order to redistribute blood flow. The distribution of microspheres was initially assessed by using technetium-99m-labeled macroaggregated albumin (^99mTc-MAA) from one of two vascular points before the administration of yttrium-90 (⁹⁰Y)-radiolabeled resin microspheres. Perfusion of lesions situated in the redistributed segments (L-RS) and nonredistributed segments (L-NRS) were compared by assessing the distribution of ^99mTc-MAA by SPECT/CT. Perfusion was graded as normal, reduced, or absent. ⁹⁰Y resin microspheres were then injected from the same arterial sites as ^99mTc-MAA and the tumor response recorded 3 months later. The tumor response in L-RS was compared with that in L-NRS and graded as better, similar, or worse. Among 11 patients with type I AAP in whom mainly vessels in segments I–III or IV were occluded, perfusion of L-RS was graded as similar (n = 7) or reduced (n = 4). Among the remaining 13 patients with AAP types III (n = 3), V (n = 4), VIII (n = 3), and others (n = 3) in which aberrant arteries were occluded, perfusion of L-RS was graded as similar (n = 9), reduced (n = 3), or absent (n = 1). Overall, ^99mTc-MAA was present in the L-RS of 95.8% patients and the distribution of ^99mTc-MAA in L-RS and L-NRS were graded as similar in 66.6% of patients. Compared with lesions in the L-NRS, tumor response in L-RS was similar in 23 cases and worse in 1 case. No complications were recorded after the administration of ⁹⁰Y resin microspheres. Redistribution of flow in L-RS is feasible and enables a safe and effective delivery of ⁹⁰Y resin microspheres that are able to be distributed via intrahepatic collaterals and access the microvasculature of L-RS.