Image-Guided Monitoring of Meningioma Embolization in a Combined MRI/XRA Suite

描述（由申请人提供）：脑膜瘤的诊断通常通过常规CT和/或MR成像来确定肿瘤的形态和组成。如果脑膜瘤是血管性的，并且计划切除，术前栓塞有助于减少手术时间和术中出血量。在常规实践中，进行诊断性动脉造影以确定血液供应并评估栓塞的安全性和可行性，如果认为合适，则输送栓塞材料以产生断流和随后的肿瘤坏死。x射线透视具有出色的空间和时间分辨率，但由于它是一种投影方式，不能提供感兴趣区域的完整3D分析，因此受到限制。初步结果表明，与灌注MRI相比，它对造影剂转移的敏感性较低，并且提取灌注时间常数或血流速度等功能参数的能力有限。因此，x线透视可能无法识别出所有可能从栓塞中获益的患者。介入MRI因其对动脉内注射磁共振造影剂的敏感性和确定功能参数的能力而具有吸引力。然而，由于担心与热相关的损伤，适用于人类介入MRI设置的导管必须是无金属的，这限制了这项技术的广泛推广。这个项目的目的是确定磁共振灌注和x线透视在确定哪些脑膜瘤是栓塞的候选物方面的相对能力。本项目将进一步评估MR灌注时间曲线是否可以确定肿瘤血管的相对贡献来自于颈外动脉与颈内动脉，以及MR灌注时间曲线的静脉内测量是否能够提供与动脉内测量相似的数据。如果是这样的话，这个项目可以确定静脉内磁共振是否可以识别那些不适合栓塞治疗的患者，从而避免他们进行侵入性动脉造影。最后，本项目将在一系列精心控制的模型实验中，研究是否可以使用具有合适成像参数的特定脉冲序列，而不会对某些金属包覆导管造成不良加热。公共卫生相关性：本研究将确定MR是否可用于更有效地对脑膜瘤栓塞患者进行分期，如果栓塞无效则保留导管，并包括将从栓塞中获益的患者，以及仅根据x线透视评估可能无法获得获益的患者。此外，令人满意的磁共振条件证明金属包覆导管可以安全使用，这将扩大其能力，不仅用于脑膜瘤的治疗，而且用于广泛的令人兴奋的应用，这些应用目前被认为是不可接近的。本研究将确定MR是否可以更有效地用于脑膜瘤栓塞患者的分期，如果栓塞无效，则不需要导管，并包括将从栓塞中获益的患者，以及仅根据x线透视评估可能无法获得获益的患者。此外，令人满意的磁共振条件证明金属包覆导管可以安全使用，这将扩大其能力，不仅用于脑膜瘤的治疗，而且用于广泛的令人兴奋的应用，这些应用目前被认为是不可接近的。

DESCRIPTION (provided by applicant): Diagnosis of a meningioma is generally established by routine CT and/or MR imaging that determines the tumor morphology and composition. If the meningioma is fairly vascular and resection is planned, preoperative embolization is helpful in diminishing operative time and intraoperative blood loss. In routine practice, a diagnostic arteriogram is performed to identify blood supply and to assess the safety and feasibility of embolization, and if deemed appropriate, embolic material is then delivered to produce devascularization and subsequent necrosis of the tumor. X-ray fluoroscopy has excellent spatial and temporal resolution but is limited in that it is a projection modality that does not provide a full 3D analysis of the territory of interest. Preliminary results indicate that it is less sensitive to the transit of contrast material than is perfusion MRI, and has a limited ability to extract functional parameters, such as perfusion time constants or flow velocities. It is therefore likely that x-ray fluoroscopy fails to identify all patients who would benefit from embolization. Interventional MRI is attractive because of its sensitivity to intra-arterial injections of MR contrast agents and its ability to determine functional parameters. However, catheters suitable for human use in the interventional MRI setting must be metal-free because of concerns of heating-related injury, restricting the wide dissemination of this technology. The goal of this project is to determine the relative capability of MR perfusion and x-ray fluoroscopy in determining which meningiomas are candidates for embolization. This project will further assess whether MR perfusion time curves can determine the relative contribution of tumor vascularity that arises from the external versus the internal carotid artery, and whether intra-venous measurements of MR perfusion time curves are able to provide similar data to that of intra-arterial measurements. If that is the case, this project could establish whether intra- venous MR can identify those patients who are not candidates for embolization therapy, thereby sparing them an invasive arteriogram. Finally, this project will investigate, in a series of carefully controlled model experiments, whether specific pulse sequences with suitable imaging parameters can be used without causing untoward heating in certain metal-clad catheters. Public Health Relevance: This study will determine if MR can be used to more effectively stage patients for meningioma embolization, sparing patients from catheterization if embolization will not be effective, and including patients who would benefit from embolization, and who might not receive that benefit on the basis of x-ray fluoroscopy evaluation, alone. In addition, satisfactory demonstration of MR conditions under which metal-clad catheters could be safely used would enable expanded capabilities, not only for treatment of meningiomas, but in a broad range of exciting applications that are currently considered unapproachable. This study will determine if MR can be used to more effectively stage patients for meningioma embolization, sparing patients from catheterization if embolization will not be effective, and including patients who would benefit from embolization, and who might not receive that benefit on the basis of x-ray fluoroscopy evaluation, alone. In addition, satisfactory demonstration of MR conditions under which metal-clad catheters could be safely used would enable expanded capabilities, not only for treatment of meningiomas, but in a broad range of exciting applications that are currently considered unapproachable.