Vidjak Klementina, Farina Laura, Challapalli Ritihaas Surya, Quinn Anne Marie, O'Halloran Martin, Lowery Aoife, Ruvio Giuseppe, Cavagnaro Marta
Department of Information Engineering, Electronics, and Telecommunications, Sapienza University of Rome, Rome, Italy.
Endowave Ltd., Galway, Ireland.
Sci Rep. 2024 Mar 11;14(1):5940. doi: 10.1038/s41598-024-55035-3.
Microwave thermal ablation is an established therapeutic technique for treating malignant tissue in various organs. Its success greatly depends on the knowledge of dielectric properties of the targeted tissue and on how they change during the treatment. Innovation in lung navigation has recently increased the clinical interest in the transbronchial microwave ablation treatment of lung cancer. However, lung tissue is not largely characterized, thus its dielectric properties investigation prior and post ablation is key. In this work, dielectric properties of ex-vivo ovine lung parenchyma untreated and ablated at 2.45 GHz were recorded in the 0.5-8 GHz frequency range. The measured dielectric properties were fitted to 2-pole Cole-Cole relaxation model and the obtained model parameters were compared. Based on observed changes in the model parameters, the physical changes of the tissue post-ablation were discussed and validated through histology analysis. Additionally, to investigate the link of achieved results with the rate of heating, another two sets of samples, originating from both ovine and porcine tissues, were heated with a microwave oven for different times and at different powers. Dielectric properties were measured in the same frequency range. It was found that lung tissue experiences a different behavior according to heating rates: its dielectric properties increase post-ablation while a decrease is found for low rates of heating. It is hypothesized, and validated by histology, that during ablation, although the tissue is losing water, the air cavities deform, lowering air content and increasing the resulting tissue properties.
微波热消融是一种用于治疗多种器官中恶性组织的成熟治疗技术。其成功很大程度上取决于对目标组织介电特性的了解以及它们在治疗过程中的变化情况。肺部导航技术的创新最近增加了人们对经支气管微波消融治疗肺癌的临床兴趣。然而，肺组织的特征尚不明确，因此消融前后对其介电特性的研究至关重要。在这项工作中，记录了在2.45 GHz频率下未处理和已消融的离体绵羊肺实质在0.5 - 8 GHz频率范围内的介电特性。将测量得到的介电特性拟合到二极科尔 - 科尔弛豫模型，并比较得到的模型参数。基于模型参数的观察变化，通过组织学分析讨论并验证了消融后组织的物理变化。此外，为了研究所得结果与加热速率之间的联系，另外两组分别来自绵羊和猪组织的样本用微波炉以不同时间和不同功率进行加热。在相同频率范围内测量介电特性。发现肺组织根据加热速率表现出不同的行为：消融后其介电特性增加，而低加热速率下则降低。据推测，并经组织学验证，在消融过程中，尽管组织在失水，但气腔变形，空气含量降低，从而导致组织特性增加。
