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

对于微波消融治疗，所提出的双模式应用器提供了一个额外的传感模式，以改善在目标组织中的定位过程和精确的肿瘤定位。此外，该应用程序将与mri兼容，因此，通过将mri成像与集成在应用程序中的微波传感相结合，可以实现多模态成像的概念。除了具有微创和治疗时间短等优点外，它还允许在不需要CT成像的情况下进行消融治疗，因此，避免了患者和放射科医生的辐射暴露。为了优化双模应用器设计，在ESSENCE第一阶段引入的烧蚀模拟模型将进一步发展为双向模拟，考虑温度相关的组织特性，其中介电常数和对流流量系数在烧蚀过程中受到的影响。对于涂抹器测试实验，需要一个可复制的凝胶模体，它模拟人类肝脏的介电介电常数和凝血行为，以避免在人类或动物中进行实验。因此，在第一个项目阶段开发的模型的基础上，将生产一个新的模型版本，该版本将满足肝脏等效的进一步标准。最后，一个完整的肝脏模型将提供重复性实验与应用程序。为了在插入器期间获得有关组织状态的反馈，将开发一个定制的校准程序，该程序将提前应用于治疗。当涂抹器在组织内移动时，该程序允许检测电介质对比。一旦涂抹器在肿瘤组织附近，它的位置将显示给用户。涂抹器将被测试有关磁共振成像伪影和微波与磁共振扫描仪电磁场之间的相互作用。此外，核磁共振测温将在核磁共振引导消融过程中应用和测试。通过这种方式，将采取适当的措施来考虑涂抹器的mri兼容性。完整的应用器原型将最终在临床条件下应用于mr引导下的离体猪肝样本和切除的人肝组织消融实验，以评估针在组织中的处理和定位。据我们所知，本项目提出的具有诊断功能的新型双模微波消融装置之前仅由我们小组在文献中报道过。未来，所开发的双模微波应用器将显著提高微波消融治疗的疗效，并将向提供根治性治疗迈出一步，而不仅仅是用于姑息治疗。

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.