Elimination of Head Movement Artifact in fMRI

描述（由申请人提供）： 虽然功能性磁共振成像（fMRI）的后处理方法已经取得了很大的进展，但许多针对患者或儿科人群的研究仍然受到头部运动伪影的限制。来自我们小组和其他人的数据表明，磁化率效应引起的图像失真与头部位置有关。因此，我们假设，采集和处理方法的设计，以减少易失性引起的图像失真和信号空洞，并将提高重新排列运动校正方法的有效性。这项工作的长期目标是开发图像采集协议，重建方法和后处理方法，将提高在功能磁共振成像头部运动校正的有效性。我们的方法是首先全面了解采集参数运动校正的有效性、磁化率伪影最小化的采集方法以及图像重建中的磁化率校正。这将主要通过使用计算机控制的运动模型对头部运动和模型研究进行广泛的模拟研究。最有前途的方法将在人类功能磁共振成像研究中进行经验评估。我们还将开发采集和重建方法，明确允许估计和校正运动引起的磁场变化和图像失真的相关变化。最后，我们将探索方法来建模和图像重新对齐后的残留误差。减少磁化率效应的方法可以在靠近空气-组织界面的大脑区域中显示出运动校正的最大改善。这些区域包括眶额皮质、颞叶下部和内侧以及额极-大脑区域，这些区域对执行和情绪处理很重要，并与情感障碍、物质滥用和许多疾病有关。我们的综合方法-包括采集，重建和后处理方法-将允许几乎完全校正大的头部运动，使功能磁共振成像成为研究痴呆症和其他精神疾病患者以及研究儿科人群的更有用的工具。

DESCRIPTION (provided by applicant): While great gains have been made in post-processing methods for functional magnetic resonance imaging (fMRI), many studies in patient or pediatric populations continue to be limited by head motion artifact. Data from our group and others suggest that image distortions from magnetic susceptibility effects are head position dependent. Consequently, we hypothesize that acquisition and processing methods designed to reduce susceptibility-induced image distortions and signal voids and will improve the effectiveness of realignment movement correction methods. The long-term goal of this work is to develop image acquisition protocols, reconstruction approaches and post-processing methods that will improve on the effectiveness of head movement correction in fMRI. Our approach will be to first develop a comprehensive understanding of the impact on the effectiveness of motion correction of acquisition parameters, acquisition methods for minimization of susceptibility artifact, and susceptibility corrections in image reconstruction. This will be carried out mainly through extensive simulation studies of head motion and phantom studies using a computer-controlled motion phantom. The most promising approaches will be evaluated empirically in human fMRI studies. We will also develop acquisition and reconstruction methods that will explicitly allow the estimation and correction of motion-induced changes in the magnetic fields and the associated changes in image distortions. Finally, we will explore methods to model and account for residual error after image realignment. Methods that reduce magnetic susceptibility effects may show the largest improvement in motion correction in regions of the brain in close proximity to an air-tissue interfaces. These areas include the orbito-frontal cortex, inferior and medial temporal lobes, and the frontal pole - brain areas that are important for executive and emotional processing and have been implicated in affective disorders, substance abuse and numerous conditions. Our comprehensive approach - including acquisition, reconstruction and post-processing methods - will allow for nearly complete correction of large head motions, making fMRI a substantially more useful tool for studying patients with dementias and other psychiatric disorders and for studying pediatric populations.