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

描述(申请人提供)：脑膜瘤的诊断通常是通过常规的CT和/或MR成像来确定肿瘤的形态和成分。如果脑膜瘤有相当多的血管，并计划切除，术前栓塞术有助于减少手术时间和术中出血。在常规操作中，要进行诊断动脉造影，以确定血供，评估栓塞的安全性和可行性，如果认为合适，然后输送栓塞剂，以产生断流血管和随后的肿瘤坏死。X射线透视具有极好的空间和时间分辨率，但它的局限性在于它是一种投影方式，不能提供感兴趣区域的完整3D分析。初步结果表明，与灌注MRI相比，它对造影剂传输的敏感性较低，并且提取功能参数的能力有限，如灌注时间常数或血流速度。因此，X光透视很可能无法确定所有将从栓塞术中受益的患者。介入性磁共振成像因其对动脉内注射MR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，由于担心与加热相关的损伤，适合人类在介入性MRI环境中使用的导管必须是无金属的，这限制了这项技术的广泛传播。该项目的目标是确定MR灌注和X光透视在确定哪些脑膜瘤适合栓塞方面的相对能力。该项目将进一步评估MR灌注时间曲线是否可以确定来自颈外动脉和颈内动脉的肿瘤血管的相对贡献，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进行栓塞术的患者，从而避免他们进行侵入性动脉造影。最后，该项目将在一系列精心控制的模型实验中调查，是否可以使用具有合适成像参数的特定脉冲序列，而不会在某些金属包层导管中引起不适的发热。公共卫生相关性：这项研究将确定MR是否可以更有效地为脑膜瘤患者进行栓塞术，如果栓塞术无效则避免患者插管，并包括将从栓塞中受益的患者，以及仅根据X射线透视评估可能无法获得这种好处的患者。此外，令人满意的磁共振条件证明，金属包层导管可以安全使用，这将使能力扩大，不仅用于脑膜瘤的治疗，而且在目前被认为是无法达到的令人兴奋的广泛应用中。这项研究将确定MR是否可以更有效地为脑膜瘤患者进行栓塞术，如果栓塞无效则避免患者插管，并包括将从栓塞中受益的患者，以及仅凭X射线透视评估可能得不到这种好处的患者。此外，令人满意的磁共振条件证明，金属包层导管可以安全使用，这将使能力扩大，不仅用于脑膜瘤的治疗，而且在目前被认为是无法达到的令人兴奋的广泛应用中。

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.