Time-multiplexed two-channel capacitive radiofrequency XXXX with nanoparticle mediation.

@entity5 @entity221
BACKGROUND: Capacitive radiofrequency (RF) @entity221 suffers from excessive temperature rise near the electrodes and poorly localized heat transfer to the deep-seated @entity5 region even though it is known to have potential to cure ill-conditioned @entity5 . To better localize heat transfer to the deep-seated target region in which electrical conductivity is elevated by nanoparticle mediation, two-channel capacitive RF heating has been tried on a phantom. METHODS: We made a tissue-mimicking phantom consisting of two compartments, a @entity5 -tissue-mimicking insert against uniform background agarose. The @entity5 -tissue-mimicking insert was made to have higher electrical conductivity than the normal-tissue-mimicking background by applying magnetic nanoparticle suspension to the insert. Two electrode pairs were attached on the phantom surface by equal-angle separation to apply RF electric field to the phantom. To better localize heat transfer to the @entity5 -tissue-mimicking insert, RF power with a frequency of 26  MHz was delivered to the two channels in a time-multiplexed way. To monitor the temperature rise inside the phantom, MR thermometry was performed at a 3T MRI intermittently during the RF heating. Finite-difference-time-domain (FDTD) electromagnetic and thermal simulations on the phantom model were also performed to verify the experimental results. RESULTS: As compared to the one-channel RF heating, the two-channel RF heating with time-multiplexed driving improved the spatial localization of heat transfer to the @entity5 -tissue-mimicking region in both the simulation and experiment. The two-channel RF heating also reduced the temperature rise near the electrodes significantly. CONCLUSIONS: Time-multiplexed two-channel capacitive RF heating has the capability to better localize heat transfer to the nanoparticle-mediated @entity5 region which has higher electrical conductivity than the background normal tissues.
