Quantitative MR-PET for Therapy Assessment in Glioma Patients

描述(申请人提供)：磁共振成像(MRI)和正电子发射断层扫描(PET)是临床和生物医学研究应用广泛的成像技术。MRI的优势包括软组织的高分辨率和高对比度的形态成像，能够成像生理参数(即扩散、灌注)，以及使用化学位移成像测量代谢物。PET图像具有高灵敏度的生物靶向放射性示踪剂的分布，但图像通常缺乏解剖学背景，空间分辨率较低。这两种模式之间存在明显的协同作用，因为每一种模式都能提供另一种模式所不能提供的独特信息。到目前为止，PET和MR图像是在不同的成像系统上获取的，并使用软件方法进行联合配准。然而，获取PET和MRI数据的顺序排除了在时间上关联PET和MRI表现的可能性。生物系统本质上是动态的，它们对药物、造影剂和其他外部刺激的反应也可以强烈地依赖于时间。一种与MRI兼容的PET扫描仪已经为大脑应用而建造，允许同时获取两种模式的数据。这项新技术将允许采集时间相关的数据，显示PET放射性示踪剂和MRI造影剂或MR可检测代谢物的分布，并注册到潜在的解剖学。在这项提案中，我们的目标是通过一系列步骤将MR-PET仪器推向有意义的临床人类使用，从而验证这项技术，确定最佳利用组合数据的方法，并将这些方法应用于新诊断的胶质母细胞瘤(GBM)患者。我们特别注重系统产出的量化，因为许多先进的应用程序将需要完全量化的数据。具体来说，我们将：(1)评估和优化集成系统的性能。我们假设组合MR-PET扫描仪的性能将类似于目前临床和研究应用中使用的一系列协议的独立仪器的性能。(2)利用同步采集的磁共振数据验证改进PET数据量化的方法。我们假设MR信息可用于进行PET衰减和运动校正，并获得动脉输入功能的估计。(3)使用所开发的联合系统和所开发的方法对GBM患者的治疗反应进行定量MR-PET评估。我们假设，从动态PET数据分析中获得的参数可以为静态PET研究提供额外的信息，并且这些信息可以补充MRI提供的信息。公共卫生相关性：结合磁共振和正电子发射断层扫描是一项非常有前途的临床和研究应用技术。在这项工作中，我们验证了这项新技术，并探索了它在胶质瘤患者治疗反应定量评估中的潜在用途。

DESCRIPTION (provided by applicant): Magnetic resonance imaging (MRI) and positron emission tomography (PET) are widely used imaging technologies with both clinical and biomedical research applications. MRI's strengths include high resolution and high contrast morphologic imaging of soft tissues, the ability to image physiologic parameters (i.e. diffusion, perfusion) and the measurement of metabolites using chemical shift imaging. PET images the distribution of biologically-targeted radiotracers with high sensitivity, but images generally lack anatomic context and are of lower spatial resolution. There are clear synergies between the two modalities, as each can provide unique information not attainable with the other modality. To date, PET and MR images are acquired on separate imaging systems, and co registered using software approaches. However, acquiring PET and MRI data sequentially rules out the possibility of temporally correlating PET and MRI findings. Biological systems are inherently dynamic, and their response to drugs, contrast agents, and other external stimuli can also be strongly time-dependent. An MRI-compatible PET scanner has been built for brain applications that allow data from both modalities to be acquired simultaneously. This new technology will permit acquisition of temporally correlated data showing the distribution of PET radiotracers and MRI contrast agents or MR- detectable metabolites, with registration to the underlying anatomy. In this proposal we aim to advance this MR-PET instrumentation toward meaningful clinical human use by a series of steps whereby we will validate this technology, identify methods to best exploit the combined data, and apply these methods to patients with newly diagnosed glioblastoma (GBM). We particularly seek to focus on quantitation of the output of the system because many advanced applications will require fully quantitative data. Specifically, we will: (1) Assess and optimize the performance of the integrated system. We hypothesize the performance of the combined MR-PET scanner will be similar to that of the stand-alone instruments for a range of protocols currently in use for clinical and research applications. (2) Validate methods to improve the quantification of the PET data using the simultaneously acquired MR data. We hypothesize that the MR information can be used to perform PET attenuation and motion correction and to obtain an estimate of the arterial input function. (3) Use the combined system and the methods developed for performing quantitative MR-PET assessment of response to therapy in GBM patients. We hypothesize that parameters derived from the dynamic PET data analysis may provide additional information to static PET studies, and that this information may supplement the information provided by the MRI. PUBLIC HEALTH RELEVANCE: Combined magnetic resonance and positron emission tomography is a very promising technology for clinical and research applications. In this work we validate this new technology and explore its potential utility for the quantitative assessment of therapy response in glioma patients.