Barker Jeffrey W, Han Paul Kyu, Choi Seung Hong, Bae Kyongtae Ty, Park Sung-Hong
Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
PLoS One. 2015 Feb 9;10(2):e0117101. doi: 10.1371/journal.pone.0117101. eCollection 2015.
We present a new method for magnetization transfer (MT) ratio imaging in the brain that requires no separate saturation pulse. Interslice MT effects that are inherent to multi-slice balanced steady-state free precession (bSSFP) imaging were controlled via an interslice delay time to generate MT-weighted (0 s delay) and reference images (5-8 s delay) for MT ratio (MTR) imaging of the brain. The effects of varying flip angle and phase encoding (PE) order were investigated experimentally in normal, healthy subjects. Values of up to ∼50% and ∼40% were observed for white and gray matter MTR. Centric PE showed larger MTR, higher SNR, and better contrast between white and gray matter than linear PE. Simulations of a two-pool model of MT agreed well with in vivo MTR values. Simulations were also used to investigate the effects of varying acquisition parameters, and the effects of varying flip angle, PE steps, and interslice delay are discussed. Lastly, we demonstrated reduced banding with a non-balanced SSFP-FID sequence and showed preliminary results of interslice MTR imaging of meningioma.
我们提出了一种用于脑部磁化传递（MT）比率成像的新方法，该方法无需单独的饱和脉冲。通过层间延迟时间控制多层平衡稳态自由进动（bSSFP）成像中固有的层间MT效应，以生成用于脑部MT比率（MTR）成像的MT加权图像（延迟0秒）和参考图像（延迟5 - 8秒）。在正常健康受试者中通过实验研究了不同翻转角和相位编码（PE）顺序的影响。白质和灰质MTR值分别高达约50%和约40%。与线性PE相比，中心PE显示出更大的MTR、更高的信噪比以及白质和灰质之间更好的对比度。MT双池模型的模拟结果与体内MTR值吻合良好。模拟还用于研究不同采集参数的影响，并讨论了不同翻转角、PE步数和层间延迟的影响。最后，我们展示了使用非平衡SSFP - FID序列减少条纹的情况，并展示了脑膜瘤层间MTR成像的初步结果。
