Obara Makoto, Kuroda Kagayaki, Wang Jinnan, Honda Masatoshi, Yoneyama Masami, Imai Yutaka, Van Cauteren Marc
Philips Electronics Japan Ltd., Healthcare, Shinagawa, Tokyo, Japan; Course of Science and Technology Graduate School of School of Science and Technology, Tokai University, Hiratsuka, Kanagawa, Japan.
J Magn Reson Imaging. 2014 Oct;40(4):824-31. doi: 10.1002/jmri.24430. Epub 2013 Nov 4.
To investigate the image quality impact of a new implementation of the improved motion-sensitized driven-equilibrium (iMSDE) pulse scheme in the human brain at 3.0 Tesla.
Two iMSDE preparation schemes were compared; (a) iMSDE-1: two refocusing pulses and two pairs of bipolar gradients and (b) iMSDE-2: adding extra bipolar gradients in front of the iMSDE-1 preparation. Computer simulation was used to evaluate the difference of eddy currents effect between these two approaches. Five healthy volunteers were then scanned with both sequences in the intracranial region and signal changes associated with iMSDE-1 and iMSDE-2 were assessed and compared quantitatively and qualitatively.
Simulation results demonstrated that eddy currents are better compensated in iMSDE-2 than in the iMSDE-1 design. In vivo comparison showed that the iMSDE-2 sequence significantly reduced the tissue signal loss at all locations compared with iMSDE-1 (5.0% versus 23% in average, P < 0.0002 at paired t-test). The signal in iMSDE-1 showed greater spatial inhomogeneity than that of iMSDE-2.
Our results show that iMSDE-2 demonstrated smaller loss in signal and less spatial variation compared with iMSDE-1, we conjecture due to the improved eddy current compensation.
研究在3.0特斯拉条件下，改进的运动敏感驱动平衡（iMSDE）脉冲序列新实施方案对人脑图像质量的影响。
比较了两种iMSDE准备方案；（a）iMSDE - 1：两个重聚焦脉冲和两对双极梯度；（b）iMSDE - 2：在iMSDE - 1准备方案前增加额外的双极梯度。采用计算机模拟评估这两种方法在涡流效应方面的差异。然后对5名健康志愿者的颅内区域用这两种序列进行扫描，并对与iMSDE - 1和iMSDE - 2相关的信号变化进行定量和定性评估与比较。
模拟结果表明，iMSDE - 2对涡流的补偿优于iMSDE - 1设计。体内比较显示，与iMSDE - 1相比，iMSDE - 2序列在所有位置均显著减少了组织信号损失（平均分别为5.0%和23%，配对t检验P < 0.0002）。iMSDE - 1中的信号比iMSDE - 2表现出更大的空间不均匀性。
我们的结果表明，与iMSDE - 1相比，iMSDE - 2的信号损失更小，空间变化更小，我们推测这是由于涡流补偿得到了改善。
