MR-Guided Endovascular Intervention Using Off-Resonance Contrast Angiography

使用非共振造影血管造影的 MR 引导血管内干预

• 批准号: 7588560
• 负责人: Robert R. Edelman
• 金额: $ 22.88万
• 依托单位: NORTHSHORE UNIVERSITY HEALTHSYSTEM
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7588560
• 关键词: Address; Angiography; Area; Catheterization; Catheters; Contrast Media; Dependence; Diagnosis; Family suidae; Fatty acid glycerol esters; Frequencies; Future; Gadolinium; Gadolinium DTPA; Image; Imagery; Imaging Techniques; Infusion procedures; Intervention; Investigation; Lead; Length; Magnetic Resonance; Magnetic Resonance Imaging; Magnetism; Mainstreaming; Measurable; Measurement; Measures; Methodology; Methods; Modeling; Morphologic artifacts; Nylons; Organ; Outcome; Outcome Study; Patients; Physiologic pulse; Predisposition; Procedures; Property; Radial; Reference Standards; Renovascular Hypertension; Research Activity; Resolution; Risk; Safety; Signal Transduction; Slide; Solutions; Structure; Surface; Techniques; Technology; Time; Tissues; Vascular Diseases; Water; abdominal aorta; base; data acquisition; design; ferumoxytol; imaging modality; improved; in vivo Model; interest; novel; novel strategies; public health relevance; radiofrequency; renal artery; treatment strategy

DESCRIPTION (provided by applicant): We propose the use of a new contrast mechanism, Off Resonance Contrast Angiography (ORCA), to facilitate MR-guided endovascular procedures. ORCA relies on the observation that a paramagnetic contrast agent (such as gadolinium-DTPA) induces a frequency shift due to the bulk magnetic susceptibility effect of gadolinium. In essence, ORCA "tunes in" the desired structures while "tuning out" signals from other tissues. The method shows great promise for visualization and real-time tracking of angiographic catheters. ORCA is particularly attractive for MR-guided endovascular procedures for several reasons: (1) standard angiographic catheters containing low concentrations of gadolinium chelate are depicted with high conspicuity on projection images; (2) it enables real-time catheter tracking using a sliding window radial acquisition without undersampling artifact; (3) background tissues can be completely suppressed even after repeated infusions of contrast agent. In this proposal, we will evaluate BMS-induced frequency shifts using "off the shelf" contrast agents, develop novel catheter designs and coatings that exploit the ORCA effect, and implement an ultra-fast MRI pulse sequence that incorporates real-time frequency adjustment for catheter tracking. Our aims are as follows: Specific Aim 1: Parameterize the ORCA effect and determine the lowest concentration of contrast agent that allows adequate visibility of an MRI compatible catheter at 1.5 Tesla. Tasks involve: (1) systematically varying the concentrations of two MRI contrast agents, gadolinium-DTPA and ferumoxytol, to determine which holds the most promise for improving the conspicuity of catheters for interventional MRI, (2) designing radiofrequency pulses with properties that optimize catheter-to-background contrast. Specific Aim 2: Maximize catheter conspicuity using off-resonance imaging and modified catheter designs. Tasks involve: (1) measuring the resonance frequency of spins within and surrounding the lumen of a nylon catheter containing a dilute solution of paramagnetic contrast agent; (2) applying spherically-symmetrical frequency-shifting coatings to the surface of the guidewire in order to minimize orientation-dependence of the frequency shift and catheter conspicuity Specific Aim 3: Compare the utility of off-resonance and T1-dependent methods for passive catheter tracking using an in vivo model. Tasks will involve: (1) measurement of visualized catheter length and spatial fidelity using high frame-rate off-resonance and T1-based methods. A static, high-resolution 3D trueFISP acquisition will be the reference standard; (2) demonstrate capability for facilitating renal artery catheterization, comparing outcomes between the techniques using efficacy and safety as endpoints. PUBLIC HEALTH RELEVANCE We have developed a novel magnetic resonance technology that could have broad applications to the diagnosis and therapy of vascular disorders. This study will result in a better understanding of the basic contrast mechanisms and will lead to improved treatment strategies for renovascular hypertension using MR-guided interventional procedures.

描述（由申请人提供）：我们建议使用一种新的造影机制，即非共振造影血管造影（ORCA），以促进 MR 引导的血管内手术。 ORCA 依赖于顺磁造影剂（例如钆-DTPA）由于钆的体磁化率效应而引起频移的观察结果。本质上，ORCA“调节”所需的结构，同时“调节”来自其他组织的信号。该方法在血管造影导管的可视化和实时跟踪方面显示出巨大的前景。 ORCA 对于 MR 引导的血管内手术特别有吸引力，原因如下：(1) 含有低浓度钆螯合物的标准血管造影导管在投影图像上高度显着地描绘； (2) 它能够使用滑动窗口径向采集进行实时导管跟踪，而不会出现欠采样伪影； (3)即使反复输注造影剂也能完全抑制背景组织。在本提案中，我们将使用“现成的”造影剂评估 BMS 引起的频移，开发利用 ORCA 效应的新型导管设计和涂层，并实现超快 MRI 脉冲序列，其中包含实时频率调整导管追踪。我们的目标如下： 具体目标 1：参数化 ORCA 效应并确定造影剂的最低浓度，使 MRI 兼容导管在 1.5 特斯拉时具有足够的可见度。任务包括：(1) 系统地改变两种 MRI 造影剂（钆-DTPA 和 ferumoxytol）的浓度，以确定哪一种最有希望提高介入 MRI 导管的显着性，(2) 设计具有优化导管特性的射频脉冲与背景的对比度。具体目标 2：使用非共振成像和改进的导管设计最大限度地提高导管的显着性。任务包括：（1）测量含有顺磁造影剂稀溶液的尼龙导管内腔及其周围的自旋共振频率； (2) 在导丝表面应用球对称移频涂层，以尽量减少频移的方向依赖性和导管的显着性 具体目标 3：比较非共振和 T1 相关方法对无源导管的实用性使用体内模型进行跟踪。任务将涉及：(1) 使用高帧率偏共振和基于 T1 的方法测量可视化导管长度和空间保真度。静态、高分辨率 3D trueFISP 采集将作为参考标准； (2) 展示促进肾动脉插管的能力，以功效和安全性为终点比较技术之间的结果。公共卫生相关性我们开发了一种新型磁共振技术，可广泛应用于血管疾病的诊断和治疗。这项研究将有助于更好地理解基本造影机制，并将改进使用 MR 引导介入手术治疗肾血管性高血压的策略。