Dual-mode microwave applicator for diagnosis and thermal ablation treatment of organic tissue

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For microwave ablation treatments, the proposed dual-mode applicator provides an additional sensing mode to improve the positioning procedure in the targeted tissue and precise tumor localization. Furthermore, the applicator will be MRI-compatible and thus, the concept of the multimodality imaging can be realized by combining the MR imaging with microwave sensing integrated in the applicator. In addition to the advantages like minimal-invasiveness and shorter therapy durations, it allows for an ablation therapy without need for the CT imaging, and hence, the avoidance of the radiation exposure for patients and the radiologist. For optimization of the dual-mode applicator design, the ablation simulation model introduced in the first phase of ESSENCE will be further developed towards a bidirectional simulation taking into account the temperature-dependent tissue properties among them the dielectric permittivity and convective flow coefficient that are influenced during the ablation procedure. For the applicator test experiments, a reproducible gel phantom is required which mimics the human liver regarding the dielectric permittivity and the coagulation behavior in order to avoid experiments in humans or animals. Therefore, on the basis of the phantom developed during the first project phase, a new phantom version will be produced which fulfills further criteria to be liver-equivalent. Finally, a complete liver model will be provided for reproducible experiments with the applicator. In order to get feedback about the tissue state during the applicator insertion, a tailored calibration procedure will be developed that is applied in advance to the treatment. This procedure allows the detection of dielectric contrasts when the applicator moves within the tissue. Once the applicator is in the vicinity of tumorous tissue, its position will be displayed to the user. The applicator will be tested regarding MR imaging artifacts and interaction between the microwaves and the electromagnetic fields of the MRI scanner. Furthermore, the MRI thermometry will be applied and tested during the MR-guided ablation procedure. In this way, appropriate measures will be taken concerning the MRI-compatibility of the applicator. The complete applicator prototype will be finally applied under clinical conditions in MR-guided ablation experiments to ex-vivo pig liver samples and resected human liver tissue in order to evaluate the handling and positioning of the needle in the tissue.To the best of our knowledge, the novel dual-mode microwave ablation device with diagnostic features proposed in the current project has been previously reported in literature only by our groups. In future, the developed dual-mode microwave applicator will significantly improve the efficacy of the microwave ablation therapy and will be a step forward to provide curative therapies instead of being applied only as palliative care.