Rapid, robust and non-invasive cerebral oxygenation measurements using MRI

描述（由申请人提供）：氧提取分数（OEF）是一项重要的脑氧代谢参数，为理解脑血管疾病的病理生理学、预测组织梗死和患者结局提供关键信息，并可识别将从治疗干预中获益的患者。已经证明，脑组织中氧提取分数（OEF）的升高预示着慢性动脉粥样硬化性颈动脉闭塞患者随后发生卒中的风险增加6-7倍。此外，在急性缺血性中风期间，以OEF升高和血流量减少为标志的“痛苦灌注”已被用作作为治疗性处理的靶点的“处于危险中”的组织的指标。另一方面，不加选择地治疗而不筛查“有风险”的组织可能导致严重的治疗相关并发症。因此，可以通过常规临床设置获得的可靠且非侵入性的OEF测量将对适当的患者诊断和治疗产生重大影响。尽管其重要性，脑氧合只能使用15 O正电子发射断层扫描（PET）进行量化。然而，现场回旋加速器的要求限制了150 PET测量仅在世界各地的几个医疗中心。在过去的十年中，使用磁共振成像（MRI）的非侵入性定量OEF测量已经取得了显着的技术进步。尽管已在健康人类受试者中成功获得绝对OEF测量值，但由于患者研究中特别具有挑战性的大量未解决问题，这些方法的临床实用性仍然很小。此外，尚未在患者中进行全球或区域OEF验证。在本研究中，将使用一个集成PET/MR系统（允许真正同时进行PET和MR图像采集）直接比较MR和PET OEF，而不存在与顺序成像相关的潜在混杂因素。本项目的总体目标是：（1）开发一种快速、稳健的新型MR OEF测量方法，以满足临床研究的需求;（2）在局灶性病理患者中使用同步O 15 PET测量来验证MR OEF测量。由于MR广泛可用，该项目的成功将允许在许多患者中获得PET可比OEF测量值，并为将来将该方法整合到时间敏感的患者管理决策中铺平道路。此外，该提案的技术发展-最大限度地减少MR成像伪影，提高测量效率，并协同PET和MR扫描-可以推广到许多其他神经影像学研究。

DESCRIPTION (provided by applicant): Oxygen extraction fraction (OEF) is an important cerebral oxygen metabolic parameter that provides critical information for understanding the pathophysiology of cerebrovascular disease, predicting tissue infarction and patient outcome, and may identify patients who will benefit from therapeutic intervention. It has been demonstrated that elevation of oxygen extraction fraction (OEF) in brain tissue portends a 6-7 fold increased risk of subsequent stroke in patients with chronic atherosclerotic carotid artery occlusion. Moreover, during acute ischemic stroke, "misery perfusion", marked by an elevation of OEF and decreased blood flow, has been used as an indicator of "at-risk" tissue that is a target of therapeutic treatments. On the other hand, indiscriminate treatment without screening for "at-risk" tissue may lead to serious treatment- related complications. Therefore, a reliable and non-invasive measure of OEF that can be obtained with a routine clinical setup will have a great impact on appropriate patient diagnosis and treatment. Despite its importance, cerebral oxygenation can only be quantified using 15O positron emission tomography (PET). However, the requirement of an onsite cyclotron has limited 15O PET measurements to only a few medical centers around the world. In the past decade, significant technical progress has been made towards non-invasive quantitative OEF measurements using magnetic resonance imaging (MRI). Though absolute OEF measurements have been successfully obtained in healthy human subjects, the clinical utility of these methods remains minor due to a host of unaddressed issues that are particularly challenging in patient studies. Moreover, neither global nor regional OEF validation has yet been performed in patients. In this study, an integrated PET/MR system which allows truly simultaneous PET and MR image acquisition will be utilized for a direct comparison between MR and PET OEF without potential confounding factors associated with sequential imaging. The overall objectives of this project are (1) to develop a novel MR OEF measurement that is rapid and robust to meet the need of clinical studies; and (2) to validate the MR OEF measurements using simultaneous O15 PET measurements in patients with focal pathology. Since MR is widely available, the success of this project will permit the acquisition of PET comparable OEF measurements in many patients, and pave the way for future integration of this method into time-sensitive patient management decisions. Furthermore, the technical developments from this proposal-- minimizing MR imaging artifacts, improving measurement efficiency, and synergizing PET and MR scans--can be generalized to many other neuroimaging studies.