Multi-fiber distributed temperature profiling in ex vivo magnetite nanoparticle-mediated laser tissue ablation

摘要

Laser ablation (LA) has shown promising results in selective treatment of solid tumors. Recently, nanomaterials, inparticular nanoparticles (NPs), have been proposed as mediators for laser tissue ablation due to their high opticalabsorption coefficients. In this work, we report distributed fiber optic temperature sensors for monitoring of NpmediatedLA in ex-vivo porcine liver. This study aims at improving the outcomes of LA through magnetite NpsenhancedLA with in-situ thermal profiling. Such thermal profiling is achieved with optical backscatter reflectometerinterrogating a set of custom-made MgO-doped optical fibers exhibiting enhanced scattering profiles. Fiber opticsensors, providing spatially resolved measurements, significantly outperform conventional thermocouples and imagingtechniques. A minimally invasive LA setup is based on high power fiber coupled diode laser operating at 980 nmwavelength, with output power up to 30 W. Magnetite (Fe3O4) NPs are synthetized and locally injected within the tissuebefore performing LA. The sensing setup utilizes optical backscatter reflectometer that exploits Rayleigh backscatteringto measure the temperature distribution with submillimeter spacing. Thermal maps, i.e. temperature distribution as afunction of space and time, are reported highlighting thermal distribution within the ablated lesion and in off-targetadjacent tissue. The influence of laser power and of NPs concentrations on the outcomes of LA is also investigated.Results demonstrate that injection of NPs into targeted area helps enhance conversion of light energy into thermalenergy, thus increasing the efficacy of the ablation within the treated area, without overheating the adjacent off-targettissue.