Development of Arterial Spin Labeling for Clinical Applications

描述（由申请人提供）：中风是一种破坏性疾病，由大脑灌注不足引起，是美国第三大死亡原因。动脉自旋标记（ASL）是一种基于MRI的灌注非侵入性成像方法，不使用辐射和注射，并具有巨大的潜力，有助于诊断和治疗中风。该项目的总体目标是开发两种新的ASL方法用于评估脑血管疾病，其中卒中是主要关注点。第一种是速度选择性ASL（VSASL），它解决了传统ASL技术在存在侧支和/或慢血流（中风患者中经常存在的一种情况）时无法测量脑灌注的问题。在常规ASL中，射频脉冲磁性标记通向大脑的主要动脉中的动脉血。在缓慢或侧支流动的条件下，以大约一秒的半衰期衰减的标签可以在其可以被递送到靶组织之前消散，并且可以给出没有灌注的错误阅读。在VSASL中，动脉血液纯粹基于流速而不是位置进行标记，从而允许同时在所有位置进行标记。VSASL是目前唯一的ASL技术，原则上可以在这些条件下提供准确的灌注测量。我们将VSASL引入临床实践的具体目标是：1）开发一种用于VSASL的稳健3D图像采集方法; 2）开发一种方向无关的VSASL标记方法; 3）优化VSASL以检测慢流。这项工作的结果将是一个强大的ASL方法定量灌注成像中风。第二种方法是血管源成像（VSI），其允许识别向感兴趣组织供应血液的血管源。VSI是一种新技术，具有广泛的潜在临床应用，包括颈动脉狭窄的评估，中风的风险评估和肿瘤血供的识别。VSI还处于开发的早期阶段，我们在这一领域的目标是解决两个基本的技术问题：1）基于伪连续标记优化VSI标记参数; 2）开发有效的VSI编码方案，以最大限度地提高VSI测量的SNR，并允许同时编码多个动脉。这项工作的结果将是强大的方法，不仅用于测量灌注量，而且还用于测量灌注来源的血管源。

DESCRIPTION (provided by applicant): Stroke is a devastating disease that is caused by a lack of perfusion to the brain, and is the third leading cause of death in the US. Arterial spin labeling (ASL) is an MRI based method for noninvasive imaging of perfusion, using no radiation and no injections, and holds tremendous potential for aiding in the diagnosis and management of stroke. The overall objective of this project is to develop two new ASL methods for the evaluation of cerebrovascular diseases, with stroke as the primary focus. The first is Velocity Selective ASL (VSASL), which addresses the inability of conventional ASL techniques to measure cerebral perfusion in the presence of collateral and/or slow flow, a condition that is often present in stroke patients. In conventional ASL, radiofrequency pulses magnetically tag arterial blood in major arteries leading to the brain. Under conditions of slow or collateral flow, the tag, which decays away with a half life of approximately one second, can dissipate before it can be delivered to the target tissue, and can give a false reading of no perfusion. In VSASL, arterial blood is tagged based purely on flow velocity, rather than location, allowing for tagging in all locations simultaneously. VSASL is currently the only ASL technique that can in principle give accurate measures of perfusion under these conditions. Our specific aims related to bringing VSASL into clinical practice are: 1) Development of a robust 3D image acquisition method for VSASL; 2) Development of a direction independent VSASL tagging method; and 3) Optimization of VSASL for the detection of slow flow. The result of this work will be a robust ASL method for quantitative perfusion imaging in stroke. The second method is Vascular Source Imaging (VSI), which allows for the identification of the vascular source that supplies blood to the tissue of interest. VSI is a new technique with a broad range of potential clinical applications including the evaluation of carotid stenosis, risk assessment for stroke, and the identification of tumor blood supplies. VSI is early in it's development, and our aims in this area are to address two basic technical issues: 1) Optimize VSI tagging parameters based on pseudo-continuous labeling; and 2) Develop efficient VSI encoding schemes to maximize the SNR of the VSI measurement and allow for simultaneous encoding of multiple arteries. The result of this work will be robust methods for measuring not only the amount of perfusion, but also the vascular source from which that perfusion was derived.