Fiber-Optic Distributed Sensing Network for Thermal Mapping of Gold Nanoparticles-Mediated Radiofrequency Ablation

Abstract

In this work, we report the design of an optical fiber distributed sensing network for the 2-dimensional (2D) in situ thermal mapping of advanced methods for radiofrequency thermal ablation. The sensing system is based on six high-scattering MgO-doped optical fibers, interleaved by a scattering-level spatial multiplexing approach that allows simultaneous detection of each fiber location, in a 40 × 20 mm grid (7.8 mm2 pixel size). Radiofrequency ablation (RFA) was performed on bovine phantom, using a pristine approach and methods mediated by agarose and gold nanoparticles in order to enhance the ablation properties. The 2D sensors allow the detection of spatiotemporal patterns, evaluating the heating properties and investigating the repeatability. We observe that agarose-based ablation yields the widest ablated area in the best-case scenario, while gold nanoparticles-mediated ablation provides the best trade-off between the ablated area (53.0–65.1 mm2, 61.5 mm2 mean value) and repeatability.

Optical Fiber Distributed Sensing Network for Thermal Mapping in Radiofrequency Ablation Neighboring a Blood Vessel

“…Moreover, the agarose gel provided a similar heating trend for all trials with the minimal standard deviation values. This experimental analysis shows two important conclusions: (1) The use of agarose gel substantially increases the ablated surface, as the average values rise from 25–40 mm 2 without agarose to 56–70 mm 2 with agarose; (2) The agarose gel counters the heat-sink effect significantly, resulting in ablated areas that are even larger than in absence of blood vessels (55 mm 2 average as reported in [ 12 ]). This can be explained by the fact that the medical tube has a resistance of a few tens of kΩ, but when coated with agarose gel, the impedance significantly lowers and allows heat to pass through; in this case, since we used a higher RF power, we could also obtain larger ablated surfaces.…”

“…RFA provides a treatment that combines the miniaturization of the applicator and its tip electrodes with the localization of the bio-heating process in the surrounding tissue [ 11 ], as well as allowing the ablation of large volumes. Recent studies, in addition, have shown how the use of gold [ 12 ] and silver [ 13 ] nanoparticles might significantly expand the treated area. For example, Ashikbayeva et al reported a 102% increase in the ablated surface area when using green-synthesized Ag nanoparticles in an agarose gel, and a 72% increase when using agarose only.…”