Improving the performance of diffusion-weighted inner field-of-view echo-planar imaging based on 2D-Selective radiofrequency excitations by tilting the excitation plane
Improving the performance of diffusion-weighted inner field-of-view echo-planar imaging based on 2D-Selective radiofrequency excitations by tilting the excitation plane
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DOI：
10.1002/jmri.23522
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发表时间：
2012-04-01
影响因子：
4.4
通讯作者：
Finsterbusch, Juergen
中科院分区：
文献类型：
--
作者：
Finsterbusch, Juergen
目的：为了提高基于2D选择性射频（RF）激励的扩散加权内视场（FOV）回波平面成像（EPI）的性能和灵活性，通过1）对外激励线使用更高的梯度幅度，以及2）倾斜激励平面，使得不需要的侧面激励不与当前图像切片或要采集的其他切片重叠。材料和方法：用传统的在3 T全身磁共振成像（MRI）上，比较了（未倾斜）和改进的装置，并在人脑和脊髓中进行了内部FOV扩散张量测量，体素尺寸为1.0 +/- 1.0 +/- 5.0 mm（3）和0.6 +/- 0.6 +/- 5.0 mm（3）system.Results:利用修改的设置，2D选择性RF激励可以显著缩短（例如，从26毫秒到6毫秒），这1）避免了在存在磁场不均匀性的情况下的轮廓失真，以及2）减少了所需的回波时间并相应地增加了信噪比，例如，结论：倾斜激励平面和施加可变梯度幅度提高了基于2D选择性RF激励的内FOV EPI的适用性。
Purpose: To improve the performance and flexibility of diffusion-weighted inner field-of-view (FOV) echo-planar imaging (EPI) based on 2D-selective radiofrequency (RF) excitations by 1) using higher gradient amplitudes for outer excitation lines, and 2) tilting the excitation plane such that the unwanted side excitations do not overlap with the current image slice or other slices to be acquired.Materials and Methods: Acquisitions with a conventional (untilted) and the improved setup were compared and inner FOV diffusion tensor measurements were performed in the human brain and spinal cord with voxel sizes of 1.0 +/- 1.0 +/- 5.0 mm(3) and 0.6 +/- 0.6 +/- 5.0 mm(3) on a 3 T whole-body magnetic resonance imaging (MRI) system.Results: With the modified setup, the 2D-selective RF excitations can be considerably shortened (e.g., from 26 msec to 6 msec) which 1) avoids profile distortions in the presence of magnetic field inhomogeneities, and 2) reduces the required echo time and increases the signal-to-noise ratio accordingly, e.g., by about 20% in the spinal cord.Conclusion: Tilting the excitation plane and applying variable gradient amplitudes improves the applicability of inner FOV EPI based on 2D-selective RF excitations.