A Small Surrogate for the Golden Angle in Time-Resolved Radial MRI Based on Generalized Fibonacci Sequences
A Small Surrogate for the Golden Angle in Time-Resolved Radial MRI Based on Generalized Fibonacci Sequences
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DOI：
10.1109/tmi.2014.2382572
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发表时间：
2015-06-01
影响因子：
10.6
通讯作者：
Rasche, Volker
中科院分区：
文献类型：
--
作者：
Wundrak, Stefan;Paul, Jan;Rasche, Volker
在黄金角径向磁共振成像中，恒定的111.246°的方位剖面间距保证了任意数量的径向剖面在空间中几乎均匀的方位剖面分布。尽管这种剖面顺序对各种实时成像方法都是有利的，但与平衡稳态自由进动（SSFP）序列结合使用时，由于快速切换梯度方案引入的不同涡流，大的方位角增量可能导致强烈的图像伪影。在广义Fibonacci序列的基础上，引入了一种新的小无理角序列（49.750…°，32.039…°，27.198…°，23.628…°，…）． 如果至少使用最小数量的径向剖面进行重建，则后续剖面顺序保证与黄金角相同的采样效率。建议的角度增量应用于心脏和颞下颌关节的动态成像。结果表明，对于平衡的SSFP序列，使用较小黄金角替代的轨迹可以有效地减少图像伪影，同时保持了对重建窗口宽度的自由回溯选择。
In golden angle radial magnetic resonance imaging a constant azimuthal radial profile spacing of 111.246...degrees guarantees a nearly uniform azimuthal profile distribution in -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...degrees, 32.039...degrees, 27.198...degrees, 23.628...degrees, ... ). 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.