IEEE Trans Med Imaging. 2015 Jun;34(6):1262-9. doi: 10.1109/TMI.2014.2382572. Epub 2014 Dec 18.
In golden angle radial magnetic resonance imaging a constant azimuthal radial profile spacing of 111.246...(°) guarantees a nearly uniform azimuthal profile distribution in k-space for an arbitrary number of radial profiles. Even though this profile order is advantageous for various real-time imaging methods, in combination with balanced steady-state free precession (SSFP) sequences the large azimuthal angle increment may lead to strong image artifacts, due to the varying eddy currents introduced by the rapidly switching gradient scheme. Based on a generalized Fibonacci sequence, a new sequence of smaller irrational angles is introduced ( 49.750...(°), 32.039...(°), 27.198...(°), 23.628...(°), ... ). The subsequent profile orders guarantee the same sampling efficiency as the golden angle if at least a minimum number of radial profiles is used for reconstruction. The suggested angular increments are applied for dynamic imaging of the heart and the temporomandibular joint. It is shown that for balanced SSFP sequences, trajectories using the smaller golden angle surrogates strongly reduce the image artifacts, while the free retrospective choice of the reconstruction window width is maintained.
在黄金角度放射状磁共振成像中，恒定的方位角放射状轮廓间距 111.246…（°）可确保在任意数量的放射状轮廓中，k 空间中的方位角轮廓分布几乎均匀。尽管这种轮廓顺序对各种实时成像方法有利，但与平衡稳态自由进动（SSFP）序列结合使用时，大的方位角增量可能会由于快速切换梯度方案引起的涡流而导致强烈的图像伪影。基于广义 Fibonacci 序列，引入了新的较小无理角度序列（49.750…（°）、32.039…（°）、27.198…（°）、23.628…（°）、……）。如果至少使用一定数量的放射状轮廓进行重建，那么后续的轮廓顺序可以保证与黄金角度相同的采样效率。建议的角增量用于心脏和颞下颌关节的动态成像。结果表明，对于平衡 SSFP 序列，使用较小的黄金角替代物的轨迹可以大大减少图像伪影，同时保持重建窗口宽度的自由回顾性选择。
