The Impact of Injection Distance to Bifurcations on Yttrium-90 Distribution in Liver Cancer Radioembolization

Purpose: To model the effect of the injection location on the distribution of yttrium-90 (Y-90) microspheres in the liver during radioembolization using computational simulation and to determine the potential effects of radial movements of the catheter tip. Materials and Methods: Numerical studies were conducted using images from a representative patient with hepatocellular carcinoma. The right hepatic artery (RHA) was segmented from contrast-enhanced cone-beam computed tomography scans. The blood flow was investigated in the trunk of the RHA using numerical simulations for 6 injection position scenarios at 2 sites located at a distance of approximately 5 and 20 mm upstream of the first bifurcation (RHA diameters of approximately 4.6 mm). The Y-90 delivery to downstream vessels was calculated from the simulated hepatic artery hemodynamics. Results: Varying the injection location along the RHA and across the vessel cross-section resulted in different simulated microsphere distributions in the downstream vascular bed. When the catheter tip was 5 mm upstream of the bifurcation, Y-90 distribution in the downstream branches varied by as much as 53% with a 1.5-mm radial movement of the tip. However, the catheter radial movement had a weaker effect on the microsphere distribution when the injection plane was farther from the first bifurcation (20 mm), with a maximum delivery variation of 9% to a downstream branch. Conclusions: An injection location far from bifurcations is recommended to minimize the effect of radial movements of the catheter tip on the microsphere distribution.