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Session: Poster session 2 (Odd numbers)
Session starts: Friday 27 January, 10:00
Presentation starts: 10:00

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Leonardo Bianchi (Multi-Modality Medical Imaging, Technical Medical Center, University of Twente, 7522 NB Enschede, The Netherlands)
Hindrik Kruit (Multi-Modality Medical Imaging, Technical Medical Center, University of Twente, 7522 NB Enschede, The Netherlands)
Paola Saccomandi (Department of Mechanical Engineering, Politecnico di Milano Milan, Italy)
Srirang Manohar (Multi-Modality Medical Imaging, Technical Medical Center, University of Twente, 7522 NB Enschede, The Netherlands)

Abstract:
Minimally invasive thermal therapies have gained rising acceptance as alternatives to traditional cancer surgery. Thermal techniques consist of the therapeutic application of thermal energy to induce the desired injury in the tumorous region. The provoked thermal damage in tissue is both dependent on the temperature reached and the persistence of the tissue medium at that temperature. Tissue temperatures in the hyperthermia range should be maintained for 30 – 60 min to obtain irreversible damage, whereas higher temperatures (≥ 60 °C), typically reached during thermal ablation (TA) procedures, are related to nearly instantaneous irreversible injury [1]. The main advantages of TA techniques are reduced pain, lower trauma and shorter recovery stay compared to surgery, as well as a lower requirement for radio/chemotherapy. Hence, TA methods, such as percutaneous radiofrequency ablation, are already commonly employed for the treatment of unresectable liver lesions. Nevertheless, relapses after this procedure are frequently observed due to incomplete ablation. Indeed, the effectiveness of TA procedures is still limited due to the lack of a real-time monitoring system [2]. This leads to the difficulty in delivering the proper thermal dose to completely eradicate the tumor mass, without endangering the integrity of the surrounding tissue. In this study, we devise a combined approach based on photoacoustic imaging and quasi-distributed temperature sensors, to assess and monitor the thermal effect on ex vivo hepatic tissue undergoing TA. The temperature sensors are based on fiber Bragg grating (FBG) etched in optical fibers. Photoacoustic signals arising from two different wavelengths (i.e., 760 nm and 970 nm) are acquired to allow for image guidance of the ablation device, identification of the ablation region, along with estimation of the ablation zone progression during the treatment. The FBG thermometers provide real-time feedback on the tissue temperature variation. Hence, exploiting the multiplexing and multipoint measurements capability of these sensors, spatially resolved two-dimensional thermal maps within the ablated tissue are reconstructed, during the procedure, through the analysis of the optical spectra registered by the FBG array. This preliminary study sets the basis for the establishment of a multi-sensor platform for fine-tuning TA procedures for the eradication of tumor lesions.