Quantative MR-Guided Thermal and Electromagnetic Mapping of RF Ablations

描述(由申请人提供)：射频消融术(RFA)正在成为一种有效的图像引导微创治疗癌症肿瘤外科治疗的替代方案。射频消融术似乎非常适用于不能切除的肝脏肿瘤。消融过程高度依赖于这些组织的电导率，但没有简单的方法来预测当前的路径或电流将如何集中在肿瘤上。例如，骨头和脂肪口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一种MRI系统来提高肿瘤消融的计划和效果，该系统可以在消融过程中绘制射频消融的当前路径，并绘制热变化图。射频电流图将显示能量储存的位置，磁共振测温仪将显示消融过程中热量流动的位置。我们的方法利用了一种新的磁共振成像技术，可以对组织中的射频电流密度进行成像。在MRI扫描仪的谐振频率处向消融电极注入射频电流。核磁共振扫描仪可以直接成像与消融电流相关的强磁场，然后得出组织中的电流流图。在我们的初步工作中，我们已经可视化了MR兼容消融电极中的电流流动。这些测试表明，脂肪组织有效地绝缘和阻断了消融电流。此外，电流通路本身照亮了高传导性组织，并在医学上形成了显著的对比。为了充分利用这一能力，我们将把射频电流标测与磁共振测温和消融设备结合起来，形成一个全面的介入性磁共振射频消融系统。将开发增强的射频硬件、脉冲序列和重建。完成后，我们将进行体外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为消融提供更好的治疗计划，并随着肿瘤消融的进展提供更好的时间和空间监测。MR引导的射频消融术为患者提供了一种有效的癌症肿瘤微创治疗选择和更可控的治疗方法。

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.