Abstract
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.
Radiofrequency ablation combined with conductive fluid-based dopants (saline normal and colloidal gold): Computer modeling and ex vivo experiments.