Feasibility of temperature monitoring based on radiological imaging during thermal ablation procedures on biological tissues

Minimally invasive ablation techniques are nowadays part of the clinical practice in the field of oncological treatments. Thanks to the technological improvements, thermal energy delivered through a needle allows to destroy malignancies without requiring a traditional open surgical approach. However, to safely perform these procedures it is crucial to monitor the temperature distribution into the treated tissues, in order to reach the target temperature able to destroy malignant cells and to preserve healthy surrounding structures. Real time tissue temperature monitoring can be obtained with invasive techniques (i.e. thermocouples and fiber optic sensors directly inserted close to the ablation area) and non-invasive techniques (i.e. imaging scans based on radiological techniques as Computed Tomography, Magnetic Resonance and Ultrasound). In this research project, first of all it has been investigated the role of Fiber Bragg grating sensors for temperature monitoring in ex vivo and in vivo biological tissues and then it has been assessed the feasibility of imaging based thermometry on ex vivo biological tissues (i.e. swine pancreas and livers) during ablation procedures performed with different forms of energy sources routinary applied in the clinical practice (i.e. Laser, Radiofrequency, Microwaves). The variations of Hounsfield Units on Computed Tomography, signal-to-noise ratios on Magnetic Resonance and shear wave velocities on Ultrasound have prooven to be reliable with tissue temperature changes occurring during thermal ablations (>60°C); mathematical equations to obtain tissue temperature values based on radiological imaging parameters have been so developed. According to the results provided, specially from experimental sessions on Computed Tomography and Magnetic Resonance, real time imaging based thermometry seems to be a safe and feasible biomedical methodology which could significantly improve the actual ablation settings and furthermore could lead the operators to treat a wider spectrum of malignant lesions sparing healthy tissues. Further studies on Ultrasound are necessary to make this technique applicable in clinical settings.