## 3 Results
### Volume Rendering Images and Streamlines  
Volume rendering images for the mass fraction of agents and streamlines were depicted using CFD-POST (2019 R1, ANSYS Inc., Canonsburg, PA, USA) to visualize the distribution and locus of fluids. Figure 8a,b show the volume-rendering images of \(Y_{0}\) and streamlines that originate from the catheter tip in model A0 with the boundary condition of syringe driver injection, respectively. The volume-rendering images and streamlines revealed that the agent flowed toward the peripheral region in the ECA immediately after the injection, and the agent was distributed along the streamlines. Figure 8c shows streamlines that originate from the catheter tip in model A0 with manual injection. This figure revealed that the flow field in the vessel was significantly modified by the inflow of the  
Figure 7: The distribution rate of anticancer agent and blood at the LA and FA in models B0–B3. agent from the catheter tip. The streamlines directly moved toward the LA and FA. Moreover, a few of them headed for the ICA. Figure 9a shows volume-rendering images for the mass fraction of the agent in model A1. Figure 9b,c show contour plots of the mass fraction of the agent and blood in the linguofacial trunk in model A1, respectively. Figure 9d,e shows streamlines toward the LA and FA, respectively. These images revealed that the streamlines toward the LA and FA, the outlets at which the inflow of agent was observed, passed through the vicinity of the catheter tip. Moreover, the mass fraction of the agent was observed along the streamlines. In models A2-A5, all streamlines toward the LA and FA passed through the vicinity of the catheter tip, similar to those in model A1. Figure 9b,c demonstrate that the flow of agent and blood is divided into the flow toward the FA and the one toward the LA in the linguofacial trunk. Figure 8: Volume-rendering image and streamlines in model A0. (**a**) Volume-rendering image of the mass of agent in model A0 with injection condition of the syringe driver, (**b**) streamlines originate from the catheter tip in model A0 with injection conditions of the syringe driver, (**c**) streamlines originate from the catheter tip in model A0 with injection conditions of the syringe driver. The number of figures shows the distribution rate of the agent. FA, facial artery; LA, lingual artery. Figure 9: Volume-rendering image, contour plots, and streamlines in model A1. (**a**) Volume-rendering image of the mass fraction of agent in model A1, (**b**) contour plot of the mass fraction of agent in the linguofacial trunk in model A1, (**c**) contour plot of the mass fraction of blood in the linguofacial trunk in model A1, (**d**) streamlines toward the LA in model A1, (**e**) streamlines toward the FA in model A1. The number of figures shows the distribution rate of the agent. FA, facial artery; LA, lingual artery. Figure 10a shows the volume-rendering image of the mass fraction of agent in model B0 with the condition of syringe driver. Figure 10b,c shows the streamlines toward the FA and LA, respectively. Figure 10d shows the streamlines that originate from the catheter tip in model B0 with the boundary condition of manual injection. Figure 10a-c revealed that the streamlines toward the FA and LA both passed through the vicinity of the catheter tip. In contrast, in Figure 10d, the streamlines from the catheter tip directly headed for the LA and FA the same as those in model A0 (Figure 8c). Figure 11a shows the volume-rendering image of the mass fraction of the agent in model B3. Figure 11b,c show the contour plots of the mass fraction of agent and blood in the common trunk in model B3, respectively. Figure 11d,e show streamlines toward the FA and LA in model B3, respectively. Figure 11a,b reveal that the mass fraction of the agent is distributed in the upper region of the linguofacial trunk, and no mass fraction of the agent can be seen in the vicinity of the LA in model B3. Figure 11b,c highlights this finding; the mass fraction of the agent is 0 in the LA.