QUANTITATIVE MAGNETIC RESONANCE IMAGING OF PERFUSION

描述：(改编自申请者摘要)：本报告的目的 工作是开发定量的非侵入性成像技术 利用磁共振成像进行组织灌流。这样做的动机是 项目的应用类别太多：灌注成像的临床应用 用于急性中风的非侵入性诊断和治疗评估；以及 脑功能灌注图，无论是临床应用 例如神经外科手术前的计划，或用于大脑功能的基础研究。 使用的灌注成像技术是基于磁性标记的 使用射频脉冲的动脉水。当前基于MRI的技术 可以生成灌注图，但不准确，不省时，也不 适用于多切片或3D采集。有几种效果包括 现有技术的准确性包括：对标签的误解 血液作为切片的灌流而通过切片的血液；空间上的 在施加动脉标签和 标记血液进入成像切片；标记水的交换 在血管和血管外腔之间有不同的 弛豫参数和磁化传递(MT)效应。第一 该项目的目标是设计出测量这些参数的成像技术 效果，使用梯度和射频脉冲的组合来 选择性地破坏来自特定质子群的信号，以及 控制动脉标签的特性。重大进展 已经在单独解决其中一些影响方面取得了进展，但没有 单一的技术可以声称是真正的定量。几乎可以肯定的是 将需要一系列成像技术来严格控制 所有的混杂效应，以及由此产生的血流灌注检查 将耗费大量的时间。这方面的第二个总体目标是 项目的目的是探索最小化而不是测量这些问题的技术 为了创建时间有效的灌流而产生的混杂效果 测量，并将这些与所描述的更严格的技术进行比较 以量化可能引入到灌注测量中的误差。 第三个目标是探索将这些技术扩展到 多切片或3D。这个扩展并不像大多数情况下那样简单 成像技术，因为标签方案和MT的性质 影响，并将需要特别注意测量的过境延误 MT效应的频率依赖性。最后，在以下应用程序中 感兴趣的量是血流灌注的动态变化，如功能 急性卒中的影像或治疗、血氧变化和 传输时间会混淆血流灌注量的测量和分离 这些来自灌注测量的影响是第四个目标。

DESCRIPTION: (Adapted from Applicant's Abstract): The objective of this work is to develop techniques for quantitative non-invasive imaging of tissue perfusion using magnetic resonance imaging. The motivation for this project is too classes of applications: clinical use of perfusion imaging for non-invasive diagnosis and evaluation of therapy in acute stroke; and functional perfusion mapping of the brain, either for clinical applications such as pre-neurosurgical planning, or for basic studies of brain function. The perfusion imaging techniques used are based on magnetic labeling of arterial water using radiofrequency pulses. Current MRI based techniques can generate perfusion maps, but are inaccurate, not time efficient, and not amenable to multislice or 3D acquisition. Several effects comprise the accuracy of existing techniques including: misinterpretation of labeled blood that is passing through a slice as perfusion of the slice; a spatially varying transit delay between the application of the arterial tag and the arrival of tagged blood into the imaging slice; exchange of tagged water between vascular and extravascular compartments which have different relaxation parameters; and magnetization transfer (MT) effects. The first goal of this project is to devise imaging techniques that measure these effects, using combinations of gradient and radiofrequency pulses to selectively destroy signal from specific populations of protons, and controlling the characteristics of the arterial tag. Significant progress has been made in addressing some of these effects individually, but no single technique can claim to be truly quantitative. It is almost certain that a series of imaging techniques will be required to strictly control for all of the confounding effects, and that the resulting perfusion examination will be prohibitively time consuming. The second general goal of this project is to explore techniques that minimize, rather than measure, these confounding effects in the interest of creating a time efficient perfusion measurement, and compare these to the more rigorous techniques described above to quantify possible errors introduced into the perfusion measurement. The third goal is to explore methods for extension of these techniques to multislice or 3D. This extension is not straightforward as it is in most imaging techniques, because of the nature of the tagging schemes and MT effects, and will require particular attention to measured transit delays and the frequency dependence of MT effects. Finally, in applications where the quantity of interest is dynamic changes in perfusion, such as functional imaging or treatment of acute stroke, changes in blood oxygenation and transit times can confound the perfusion measurement, and separation of these effects from the perfusion measurement is a fourth goal.