4D Flow MRI for characterization of brain arteriovenous malformations

项目摘要 脑动静脉畸形(AVM)是一种先天性脑血管畸形，易患脑血管畸形。 血管性动脉瘤、出血性中风和癫痫发作。这通常发生在10-40岁之间，使 AVM是一种不可预测的、具有潜在破坏性的情况，发生在年轻的、以前没有症状的患者中.这个 目前动静脉动静脉畸形评估和手术计划的临床标准是得出形态和主观血流 数字减影血管造影术(DSA)的参数--一种使用辐射的有效但有创的技术 和对比度。本项目的目标是开发一种用于AVM成像的优化的4D Flow MRI序列 血流动力学，以便提供净流量、流量分布、峰值速度和 AVM的压力降，并在AVM治疗过程中跟踪这些参数。 4D Flow MRI是Markl实验室开发的一种方法，用于获得时间和空间分辨率的三维图像。 来自无对比磁共振扫描的三维血流速度数据。将这种方法应用于神经血管 成像和AVM具体地说，目标是减少总成像和处理时间，同时增加空间 考虑到小血管的分辨率，增加测量速度的动态范围以适应 动静脉动静脉畸形的生理学和维持血流图像的临床应用。该项目不仅包括先进的核磁共振成像 序列开发，但也依赖于与临床医生的密切合作，以确保序列 优化以提供可在临床上用于动静脉畸形评估和治疗的信息类型。 第一个目标是开发具有适当欠采样技术和数据收集的序列 参数，以及基于网络的、简化的数据处理方法。选择设计标准是为了 能够同时显示AVM的主要供血血管和评估心脏内的搏动性血流 周而复始。第二个具体目标是在体外验证所开发的序列和数据处理方法， 模型系统具有与实际动静脉动静脉畸形相似的流动特性，并在健康志愿者体内进行。使用 现有的与MRI兼容的流动泵，具有生理流型和定制的3D打印流动室(MRI Phantom)，我们将测试开发的序列的性能，并比较结果测量结果 要使使用虚线几何体计算的真值接地。然后，将招募10名健康志愿者进行 一项重测再现性研究，以评估研究间的平均差异和一致性限度。第三个目标 通过一项小型先导性研究，对开发的序列和数据处理方法在AVM患者中进行了验证。 10名成年AVM患者将在西北纪念医院招募。患者将在治疗前接受扫描 第一次治疗以及每一次栓塞术后。通过合作医生的反馈， 从扫描中获得的新信息的潜在临床效用将得到评估和优化。 最终的目标是为AVM创建一种可靠的成像方法来补充所获得的信息 来自DSA的数据，并提供对AVM血流动力学的准确评估和整个治疗过程中的变化。

Project Summary Cerebral arteriovenous malformation (AVM) is a congenital cerebrovascular malformation that predisposes to vascular aneurysm, hemorrhagic stroke, and seizures. This typically occurs between ages 10 – 40, making AVM an unpredictable, potentially devastating condition in young, previously asymptomatic patients. The current clinical standard in AVM evaluation and surgical planning is to derive morphology and subjective flow parameters from digital subtraction angiography (DSA) – an effective but invasive technique that uses radiation and contrast. The goal of this project is to develop an optimized 4D flow MRI sequence for imaging AVM hemodynamics, in order to provide quantitative metrics of net flow, flow distribution, peak velocity, and pressure drop across the AVM, and to track these parameters throughout AVM treatment. 4D flow MRI is a method developed in the Markl lab to obtain temporally- and spatially-resolved three- dimensional flow velocity data from a contrast-free MRI scan. In adapting this approach for neurovascular imaging and AVM specifically, the aim is to reduce total imaging and processing time while increasing spatial resolution to account for small vessels, increasing dynamic range of measured velocities to accommodate AVM physiology, and maintaining clinical utility of flow images. This project will not only include advanced MRI sequence development, but also rely on close collaboration with clinicians to ensure that the sequence is optimized to provide types of information that can be clinically useful in AVM evaluation and treatment. The first aim is development of a sequence with an appropriate undersampling technique and data collection parameters, as well as a network-based, streamlined data processing method. Design criteria are chosen to enable both visualization of main feeding vessels of an AVM and evaluation of pulsatile flow within a cardiac cycle. The second specific aim is validation of the developed sequence and data processing method in vitro, with a model system with flow properties similar to actual AVMs, and in vivo, in healthy volunteers. Using an existing MRI-compatible flow pump with physiological flow profile and a custom 3D-printed flow chamber (MRI phantom), we will test the performance of the developed sequence and compare the resulting measurements to ground truth values calculated using the phantom geometry. Then, 10 healthy volunteers will be recruited for a test-retest reproducibility study to assess inter-study mean differences and limits of agreement. The third aim is validation of the developed sequence and data processing method in AVM patients, via a small pilot study. 10 adult AVM patients will be recruited at Northwestern Memorial Hospital. Patients will be scanned prior to first treatment as well as after each embolization step. Through feedback from collaborating physicians, the potential clinical utility of the new information obtained from the scan will be evaluated and optimized. Ultimately, the objective is to create a reliable imaging method for AVM to supplement information obtained from DSA, and to provide an accurate evaluation of AVM hemodynamics and changes throughout treatment.