Quantative MR-Guided Thermal and Electromagnetic Mapping of RF Ablations

描述（由申请人提供）：射频消融术（RFA）作为一种有效的图像引导微创治疗癌症肿瘤替代手术治疗。射频消融术似乎很适合肝脏不可切除的肿瘤。消融过程高度依赖于这些组织的电导率，但目前还没有简单的方法来预测电流路径或电流在肿瘤上的聚焦程度。例如，骨骼和脂肪袋可以保护肿瘤免受消融电流的影响。我们的目标是通过使用磁共振成像系统来增强肿瘤消融的计划和疗效，该系统可以绘制射频消融过程中的电流路径并绘制热变化。射频电流图将显示能量沉积的位置，磁流变温仪将显示烧蚀过程中热量流动的位置。我们的方法利用了一种新的MRI技术，可以对组织中的射频电流密度进行成像。烧蚀电极以磁共振扫描仪的共振频率注入射频电流。MRI扫描仪可以直接成像与消融电流相关的强磁场，然后得出组织内的电流流图。在我们的初步工作中，我们已经可视化了磁共振兼容消融电极中的电流流动。这些试验表明，脂肪组织有效地隔离和阻断消融电流。此外，电流通路本身照亮了高导电性组织，并产生了医学上显著的对比。为了充分利用这一能力，我们将把射频电流测绘与磁共振测温和消融设备结合起来，形成一个全面的射频消融介入MRI系统。将开发增强的射频硬件、脉冲序列和重建。完成后，我们将进行离体组织样本和体内动物研究，以证明该系统的临床潜力。如果我们实现了这些目标，MR引导的消融成像和热监测应该能够更好地为消融制定治疗计划，并随着肿瘤消融的进展提供更好的时间和空间监测。磁共振引导射频消融术为癌症肿瘤的微创治疗和更可控的治疗提供了有效的选择。

DESCRIPTION (provided by applicant): Radiofrequency ablation (RFA) is emerging as an effective image-guided minimally invasive therapeutic alternative to surgical treatment of cancer tumors. RFA appears well suited to nonresectable tumors in liver. The ablation process is highly dependent on the electrical conductivity of these tissues yet there is no easy way to predict the current pathways or how focused the current will be on the tumor. For example, bone and fatty pockets can shield tumor from ablation currents. Our goal is to enhance the planning and efficacy of tumor ablation by using an MRI system that can map RF ablation current pathways during ablation and map thermal changes. RF current maps will show where power is being deposited, and MR thermometry will show where heat flowed during the ablation. Our approach exploits a new MRI technique that images RF current density in tissue. The ablation electrode is injected with RF currents at the resonant frequency of the MRI scanner. The MRI scanner can directly image the intense magnetic fields associated with the ablation current, and then derive the map of current flow in tissue. In our preliminary work, we have already visualized the current flow in an MR compatible ablation electrode. These tests demonstrated that fatty tissue effectively insulates and blocks the ablation current. Moreover, the current pathway itself lights up high conductivity tissue and creates a medically significant contrast. To fully exploit this capability, we will merge RF current mapping with MR thermometry and ablation devices to form a comprehensive interventional MRI system for RF ablation. Enhanced RF hardware, pulse sequences and reconstructions will be developed. Upon completion, we will perform ex-vivo tissue sample and in-vivo animal studies to demonstrate the clinical potential of this system. If we achieve these goals, MR guided ablation imaging and thermal monitoring should enable better treatment planning for the ablation, and provide improved time and spatial monitoring as tumor ablation progresses. MR guided RF ablation gives the patient an effective option for a minimally invasive treatment of cancer tumors and a more controllable therapy.