Bloch simulations towards direct detection of oscillating magnetic fields using MRI with spin-lock sequence
Bloch simulations towards direct detection of oscillating magnetic fields using MRI with spin-lock sequence
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DOI：
10.1109/embc.2013.6609687
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发表时间：
2013-07
期刊：
影响因子：
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通讯作者：
S. Nagahara;Tetsuo Kobayashi
中科院分区：
文献类型：
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作者：
S. Nagahara;Tetsuo Kobayashi
使用自旋锁序列的新 MRI 方法因其检测小振荡磁场的潜力而引起了广泛关注。然而，由于涉及的机制很复杂，我们将自旋锁定序列期间的磁化性能可视化，以便通过使用矩阵运算求解瞬态布洛赫方程的快速而简单的方法，更好地理解自旋锁定脉冲与外部施加的振荡磁场的相互作用。为了改进自旋锁成像在小磁场检测中的性能（在模拟神经磁场的功能磁共振成像实验中），我们观察到这种现象会减少 MR 信号，这促使我们研究自旋锁参数如何导致 MR 信号减少；基于此，我们确定 MR 信号在与自旋锁定脉冲共振的振荡磁场中减少。我们还确定 MR 信号的减少与自旋锁持续时间成正比。我们的结果表明，MRI 可以通过使用自旋锁序列直接检测振荡磁场。
A new MRI method using the spin-lock sequence has attracted wide attention because of its potential for detecting small oscillating magnetic fields. However, as the mechanism involved is complicated, we visualized the magnetization performance during the spin-lock sequence in order to better understand interaction of the spin-lock pulse and the externally applied oscillating magnetic fields by means of a fast-and-simple method using matrix operations to solve a time-dependent Bloch equation. To improve spin-lock imaging in the detection of small magnetic fields (in an fMRI experiment that modeled neural magnetic fields), we observed that the phenomenon decreases MR signals, which led us to investigate how spin-lock parameters cause the MR signal to decrease; based on this, we determined that MR signals decrease in oscillating magnetic fields that are resonant with the spin-lock pulse. We also determined that MR signals decrease is directly proportional to spin-lock duration. Our results suggest that MRI can feasibly detect oscillating magnetic fields directly by using of the spin-lock sequence.