INTERVENTIONAL MR: ADVANCED GUIDANCE/THERMAL MONITORING

使用开放式磁体系统，我们正在开发用于指导包括热消融在内的介入性磁共振成像(IMRI)过程的方法。热消融是一种微创且经济实惠的治疗方法。介入性磁共振成像不同于诊断性磁共振成像，在我们的范例中，癌症肿瘤的微创治疗完全在磁共振成像仪中进行。MRI既能为肿瘤介入治疗提供指导，又能监测肿瘤的热疗情况。这是通过利用MRI的能力实现的：1)在肿瘤、正常组织、介入工具和热损伤之间产生对比度，以及2)获得任何角度的图像(并通过定位设备动态调整，如超声波)。然而，目前用于指导、定位和治疗监测的MRI技术存在局限性；除非克服这些限制，否则IMRI将无法实现其在微创诊断和癌症治疗程序中的巨大潜力。这些限制为开发和优化先进的磁成像脉冲序列技术创造了独特的机会，这些技术将通过更有效的IMRI功能最终改善患者护理。本项目的研究将通过解决IMRI与诊断MRI不同的四个主要问题(这些问题必须同时实现)来创建新的成像方法，以满足IMRI环境的限制：对比度：速度、运动不敏感和治疗监测。在IMRI患者中，风险与时间有关，因此我们将创建新的快速稳态自由进动成像方法，并将其具体应用于IMRI引导。与目前可用于低场动态介入应用的方法相比，它们将在组织和介入设备之间实现更好的对比度。新的径向K空间采样方法的设计和评估将比IMRI中常用的2DFT方法更好地提高设备尖端的精度并降低对运动伪影的敏感度。肝、脑、肾、胰腺、头颈部和肌肉骨骼系统是局部控制原发和转移性癌症最重要的解剖部位。该应用程序的研究将为这些解剖位置创建定制的IMRI方法，并在兔子(腹部器官中植入VX2)和猪身上进行测试。该项目将提供第一个系统研究，通过将MRI对比机制和K空间采样方案的优点结合在一起来设计低场IMRI技术，从而为每个解剖位置实现优化的IMRI方法；它们将提供比目前在几乎所有IMRI引导手术中使用的2DFT策略更好的性能。此外，该项目将改进新兴的定量磁共振热成像方法，并实现对IMRI引导的热癌症治疗的准确热监测。在我们迄今取得的成功的基础上，将制定第二代IMRI制导战略。

Using an open magnet system, we are developing methods for guiding interventional magnetic resonance imaging (IMRI) procedures including thermal ablation. Thermal ablation is minimally invasive and cost effective. Interventional MRI is different from diagnostic MRI, and in our paradigm, minimally invasive treatment of cancer tumors is performed entirely in the MR imager. MRI provides both guidance of the interventional device to the cancer tumor and monitoring the thermal treatment. This is a achieved by exploiting MRI's ability to: 1) generate contrast between tumors, normal tissues, interventional tools and thermal lesions and 2) obtain images at any angle (and dynamically adjusted, like ultrasound, via a localization device). Nonetheless, limitations exist in the current MRI techniques used for guidance, localization and treatment monitoring; unless overcome IMRI will not achieve it's vast potential in minimally invasive diagnostic and cancer treatment procedures. These limitations create a unique opportunity to develop and optimize advanced magnetic imaging pulse sequence techniques which will ultimately improve patient care through more effective IMRI capabilities. The research pursued in this project will create new imaging methods meeting the constraints of the IMRI environment by addressing four primary issues in which IMRI differs from diagnostic MRI (and these must be attained simultaneously): contrast: speed, motion insensitivity and therapy monitoring. In IMRI patient risk is related to time, and so we will create new rapid steady state free precession imaging methods with specific application for IMRI guidance. They will achieve better contrast between tissues and interventional devices than methods presently available for low field dynamic interventional applications. New radial K-space sampling methods which utilize information on the orientation of the interventional device will be designed and evaluated to improve the device tip accuracy and reduce sensitivity to motion artifacts better than 2DFT methods used commonly in IMRI. The most important anatomic locations for local control of primary and metastatic cancer are the liver, brain, kidney, pancreas, head/neck and musculoskeletal system. The research in this application will create customized IMRI methods for these anatomic locations and test them on rabbits (implanted with VX2 in the abdominal organs) and pigs. This project will provide the first systematic study in which low field IMRI techniques are designed by combining the advantages of both the MRI contrast mechanism and K-space sampling scheme together to achieve optimized IMRI methods for each anatomic location; they will offer greater performance than current 2DFT strategies used in virtually all IMRI guided procedures. Further, this project will improve emerging quantitative MR thermal mapping methods and allow attainment of accurate thermal monitoring of IMRI guided thermal cancer therapy. Based on our success to date, the second generation of IMRI guidance strategies will be created.