Adaptive Motion Correction in Functional Magnetic Resonance Imaging of Brain Activity

功能磁共振成像(FMRI)是一种生成大脑内活动图像的方法。自20世纪90年代发现以来，功能磁共振成像已经成为神经科学研究中研究人类大脑的必不可少的工具。医用功能磁共振成像应用也在开发中，例如在神经外科，神经外科医生在计划切除脑肿瘤时使用功能磁共振成像，以尽可能多地保留正常的周围组织。 不幸的是，脑活动的fMRI信号非常小，如果患者不保持头部不动，很容易受到破坏。当患者执行旨在激活特定大脑区域的任务(例如，手指运动)时，典型的功能磁共振检查需要大约5到10分钟来收集一系列图像。在此过程中，患者的头部移动不得超过一毫米。尽管各种成熟的功能磁共振成像方法可以减少头部运动的问题，比如使用光约束、快速成像(比如延时摄影，可以在不模糊的情况下冻结运动)，以及可以旋转图像并将图像转换回对齐的计算机处理方法，但总的来说，这些方法根本不够有效。 最近，研究已经开始显示“自适应功能磁共振成像”在显著减少头部运动问题方面的潜力。自适应功能磁共振成像使用位置跟踪系统在成像过程中测量头部运动，并连续调整扫描位置和方向作为补偿。在接下来的5年里，提出了一项研究，涉及使用光学位置跟踪系统来开发自适应功能磁共振成像作为一种稳健的方法。具体目标将是对单个图像切片快速执行运动校正，同时确保也补偿由于磁头运动和磁场均匀度之间以及磁头运动和信号接收器硬件之间的相互作用而产生的其他信号误差。新开发的方法将在移动测试对象和具有代表性的健康成年人和患者的功能磁共振检查中得到验证，并将在未来对更广泛的患者群体进行实用的功能磁共振检查。

Functional magnetic resonance imaging (fMRI) is method for generating pictures of activity within the brain. Since its discovery in the 1990s, fMRI has become essential in neuroscience research to investigate the human mind. Medical fMRI applications are also developing, such as in neurosurgery, where neurosurgeons use fMRI when planning to remove brain tumours, to spare as much normal surrounding tissue as possible. Unfortunately, fMRI signals of brain activity are very small and are easily corrupted if the patient does not keep their head still. A typical fMRI exam requires approximately 5 to 10 minutes for collection of a series of images while the patient performs a task (for example, finger movements) designed to activate specific brain regions. Patients must not move their head more than about a millimetre during this process. Although a variety of established fMRI methods reduce the head motion problem, such as use of light restraints, fast imaging (like time-lapse photography, which "freezes" motion without blurring), and computer processing methods that can rotate and translate images back into alignment, collectively these methods are simply not effective enough. Recently, studies have started to show the potential of "adaptive fMRI" for substantially reducing the head motion problem. Adaptive fMRI uses a position tracking system to measure head motion during imaging, and to adjust the scanning position and orientation continuously in compensation. Over the next 5 years, research is proposed that involves using an optical position tracking system to develop adaptive fMRI as a robust method. Specific goals will be to perform motion correction rapidly for individual image slices, while ensuring that other signal errors arising from the interaction between head motion and magnetic field uniformity, and between head motion and signal receiver hardware are also compensated. The newly developed methods will be validated in moving test objects and in representative fMRI exams of healthy adults and patients, and will enable practical fMRI examinations of much broader patient populations in the future.