Radioembolization of hepatic tumors: flow redistribution after the occlusion of intrahepatic arteries.

Purpose: Radioembolization using 90yttrium is an emerging therapy option for unresectable liver malignancies. In order to reduce the number of yttrium injections, endovascular occlusion of a segmental hepatic artery has been proposed. The aim of this study was to assess whether sufficient vascular redistribution of the occluded liver segments through intrahepatic collaterals can be observed.
Materials and Methods: 27 patients with hepatocellular carcinoma (n = 16) or hepatic metastases (n = 11) were studied. Hepatic angiography was performed on average 16 days prior to radioembolization. The segment II/III artery (n = 9) or the segment IV artery (n = 18) was occluded using coils. Technectium-99m-labeled macroaggregated albumin (99mTc-MAA) was injected into the right and the remaining part of the left hepatic artery in order to identify any hepatic volume not included in the perfused area. Patients underwent a SPECT/CT on average 1 h after the 99mTc-MAA injection. Two radiologists evaluated the SPECT/CT scans regarding the presence of non-perfused hepatic segments. Furthermore, hepatic perfusion was assessed by digital subtraction angiography (DSA) on the day of radioembolization.
Results: In 16/27 patients (59%) a perfusion of the occluded liver segment was visible on the SPECT/CT scan. In 8/11 patients without flow redistribution at the time of the SPECT/CT, perfusion of the occluded segment through hepatic collaterals was observed during angiography prior to radioembolization. Hence, flow redistribution was eventually found in 24/27 patients (89%).
Conclusion: Flow redistribution after the occlusion of intrahepatic arteries prior to radioembolization can be successfully induced in the majority of patients with anatomical variants of the hepatic arteries.
(© Georg Thieme Verlag KG Stuttgart · New York.)