Caren van Roekel

211 The efficacy of coil-embolization in radioembolization INTRODUCTION Radioembolization is increasingly used for the treatment of primary and secondary liver tumors. The treatment consists of an intra-arterial injection of microspheres loaded with yttrium-90 ( 90 Y) or holmium-166 ( 166 Ho). The microspheres are commonly injected in a lobar or segmental fashion (1). Injection can be challenged by the presence of early bifurcations, replaced or accessory hepatic arteries, and ‘parasitized’ arteries (i.e. non-hepatic arteries contributing to the vascular supply of the liver tumors), or by the proximity to non-target vessels. Therefore, multiple injection positions may be required. Each injection position requires a change of the vial, microcatheter, and tubing, and the injected activity needs to be adjusted to the target volume. Consequently, radioembolization procedures requiring multiple injection positions are more prone to catheter-related complications and dosing errors. Multiple injection positions are also costly due to the higher material costs and prolonged procedure time. FIGURE 1. The principle of redistribution. A typical situation with a middle hepatic artery (or segment IV artery) that would require three separate injections in case of whole- liver treatment (right hepatic artery, middle hepatic artery, and left hepatic artery). Coil-embolization of the middle hepatic artery can be performed to reduce the number of injection positions and rely on redistribution of microspheres through intrahepatic collaterals. 8