Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA.
Magn Reson Med. 2010 Oct;64(4):1121-7. doi: 10.1002/mrm.22485.
Spiral imaging is vulnerable to spatial and temporal variations of the amplitude of the static magnetic field (B(0)) caused by susceptibility effects, eddy currents, chemical shifts, subject motion, physiological noise, and system instabilities, resulting in image blurring. Here, a novel off-resonance correction method is proposed to address these issues. A k-space energy spectrum analysis algorithm is first applied to inherently and dynamically generate a B(0) map from the k-space data at each time point, without requiring any additional data acquisition, pulse sequence modification, or phase unwrapping. A simulated phase evolution rewinding algorithm and an automatic residual deblurring algorithm are then used to correct for the blurring caused by both spatial and temporal B(0) variations, resulting in a high spatial and temporal fidelity. This method is validated against conventional B(0) mapping and deblurring methods, and its advantages for dynamic MRI applications are demonstrated in functional MRI studies.
螺旋成像是容易受到静态磁场幅度的空间和时间变化的影响（B(0))由磁化率效应、涡流、化学位移、主体运动、生理噪声和系统不稳定引起，导致图像模糊。在这里，提出了一种新的离频校正方法来解决这些问题。首先应用 k 空间能量谱分析算法，从每个时间点的 k 空间数据中固有地和动态地生成 B(0)图，而无需任何额外的数据采集、脉冲序列修改或相位解缠。然后使用模拟相位演化重绕算法和自动残余去模糊算法来校正空间和时间 B(0)变化引起的模糊，从而获得高空间和时间保真度。该方法针对传统的 B(0)映射和去模糊方法进行了验证，并在功能磁共振成像研究中展示了其在动态 MRI 应用中的优势。
