Rotman Research Institute, Baycrest, Toronto, Canada.
Magn Reson Med. 2013 Mar 1;69(3):734-48. doi: 10.1002/mrm.24309. Epub 2012 May 14.
Head motion artifacts are a major problem in functional MRI that limit its use in neuroscience research and clinical settings. Real-time scan-plane correction by optical tracking has been shown to correct slice misalignment and nonlinear spin-history artifacts; however, residual artifacts due to dynamic magnetic field nonuniformity may remain in the data. A recently developed correction technique, Phase Labeling for Additional Coordinate Encoding, can correct for absolute geometric distortion using only the complex image data from two echo planar images with slightly shifted k-space trajectories. An approach is presented that integrates Phase Labeling for Additional Coordinate Encoding into a real-time scan-plane update system by optical tracking, applied to a tissue-equivalent phantom undergoing complex motion and an functional MRI finger tapping experiment with overt head motion to induce dynamic field nonuniformity. Experiments suggest that such integrated volume-by-volume corrections are very effective at artifact suppression, with potential to expand functional MRI applications.
头部运动伪影是功能磁共振成像中的一个主要问题，限制了其在神经科学研究和临床环境中的应用。光学跟踪的实时扫描平面校正已被证明可以纠正切片错位和非线性自旋历史伪影;然而，由于动态磁场非均匀性引起的残余伪影可能仍然存在于数据中。最近开发的一种校正技术，相位标记附加坐标编码，可以仅使用两个具有轻微偏移 k 空间轨迹的回波平面图像的复数图像数据来校正绝对几何变形。本文提出了一种将相位标记附加坐标编码集成到光学跟踪实时扫描平面更新系统中的方法，应用于经历复杂运动的组织等效体模和具有明显头部运动的功能磁共振手指敲击实验，以诱导动态场非均匀性。实验表明，这种容积校正方法对抑制伪影非常有效，有可能扩展功能磁共振成像的应用。
