Backflow modeling in nanofluid infusion and analysis of its effects on heat induced damage during magnetic hyperthermia

Abstract

• Simulate the backflow behavior for nanofluid infusion inside bio-tissue under a geometric nonlinear model. • Investigate the bio-tissue deformation and its effect on the change of material property during nanofluid infusion. • Investigate the interstitial pressure and the local stress distribution inside bio-tissue due to the nanofluid infusion. • Effect of backflow on treatment temperature distribution and heat induced damage for malignant tissue. Although targeted magnetic hyperthermia has been proven to be an effective tumor ablation technique, its use in clinical applications is still scarce particularly due to the difficulty in imposing a desired nanofluid distribution in the therapeutic area. In addition to the inherent difficulty of imposing a distribution with few injection shots, during the nanofluid infusion, the tissue deformation can cause the nanofluid deviation from the targeted injection area and the backflow along the needle can deliver the injected nanofluid to the outer surface of the tissue. Both phenomena can result in an irregular distribution for nanofluid inside bio-tissue. This study develops a poroelastic model considering geometrically nonlinear behavior in order to evaluate the effect of syringe needle size and infusion rate on the backflow. A 26 gauge needle for syringe is used as a typical example to further investigate the nanofluid transport and the change of solid matrix material properties under different infusion rates after comparing the infusion results for several sizes of needle. Finally, the resulting nanofluid concentration distribution obtained with the proposed model is used to simulate the temperature distribution and the cancerous cell damage. The results demonstrate that the infusion pressure and its resulting tissue deformation are the fundamental reasons for obtaining an irregular solution distribution. Tissue deformation induces the increase of porosity and permeability for biomaterials around the tip, and enhances the fluidity of nanofluids inside the tissue. The results also indicate that the increase in backflow length can improve the uniformity of the nanofluid distribution after diffusion and, consequently, the treatment effect. However, it also increases the risk of MNP leakage from the targeted area to the tumor surface, so it is important to keep the backflow rate limited during the injection process.