Background: The coagulation zone volume created during radiofrequency ablation (RFA) is limited by the appearance of roll-off. Doping the tissue with conductive fluids, e.g. gold nanoparticles (AuNPs) could enlarge the coagulation zones by delaying the roll-off. Our goal was to characterize the electrical conductivity of a substrate doped with AuNPs and to study by computer modeling and ex vivo experiments the effect on coagulation zone volumes.
Methods: The electrical conductivity of substrates doped with normal saline or AuNPs was assessed experimentally using agar phantoms. The computer models, built and solved on COMSOL Multiphysics, consisted of a cylindrical domain mimicking liver tissue and a spherical domain mimicking a doped zone with diameters of 2, 3 and 4 cm. Ex vivo experiments were conducted on bovine liver fragments and under three different doping conditions: 1) non-doped tissue (ND Group), 2 mL of 0.9% NaCl (NaCl Group), and 2 mL of AuNPs 0.1 wt% (AuNPs Group).
Results: The theoretical analysis showed that adding normal saline or colloidal gold in concentrations lower than 10% only modify the electrical conductivity of the doped substrate with practically no change of the thermal characteristics. The computer results showed a relationship between doped zone size and electrode length regarding the created coagulation zone. We observed a good agreement between ex vivo and computational results in terms of transverse diameter of the coagulation zone.
Conclusions: Both computer and ex vivo experiments showed that doping with AuNPs can enlarge the coagulation zone, specially the transverse diameter, hence achieving more spherical coagulation zones.