High slew-rate head-only gradient for improving distortion in echo planar imaging: Preliminary experience
High slew-rate head-only gradient for improving distortion in echo planar imaging: Preliminary experience
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DOI：
10.1002/jmri.25210
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发表时间：
2016-09-01
影响因子：
4.4
通讯作者：
Foo, Thomas K. F.
中科院分区：
文献类型：
--
作者：
Tan, Ek T.;Lee, Seung-Kyun;Foo, Thomas K. F.
目的研究使用专用的仅头部梯度线圈进行体内人脑成像时使用高达 700T/m/s 的高梯度转换速率 (SR) 对回波平面成像 (EPI) 失真的影响。材料和方法首先进行模拟研究以确定 EPI 中预期的回波间隔和失真减少。然后将内径为 42 厘米且具有不对称横向线圈的头部梯度安装在全身传统 3T 磁共振成像 (MRI) 系统中。对 5 名受试者进行人体成像，以确定 EPI 对不同梯度转换速率下的回波间隔和信号丢失的影响。通过梯度回波和自旋回波扩散加权 EPI 证明了 1.5mm 各向同性空间分辨率的全脑成像的可行性。结果与全身梯度线圈相比，仅头部梯度线圈中的 EPI 回波间距减小了 48%。模拟和体内结果分别显示信号丢失改善高达 25-26% 和 19%。采用 1.5mm 空间分辨率的 EPI 进行的全脑成像提供了良好的全脑覆盖、空间线性度和低空间失真效应。结论我们使用紧凑型头部梯度线圈以高于传统全身 MR 系统的转换速率进行 EPI 人脑成像，结果表明图像失真得到显着改善，并指出非 EPI 脉冲序列具有潜在的优势。 J.马格。共振。成像 2016 年；44：653-664。
PurposeTo investigate the effects on echo planar imaging (EPI) distortion of using high gradient slew rates (SR) of up to 700T/m/s for in vivo human brain imaging, with a dedicated, head-only gradient coil.Materials and MethodsSimulation studies were first performed to determine the expected echo spacing and distortion reduction in EPI. A head gradient of 42-cm inner diameter and with asymmetric transverse coils was then installed in a whole-body, conventional 3T magnetic resonance imaging (MRI) system. Human subject imaging was performed on five subjects to determine the effects of EPI on echo spacing and signal dropout at various gradient slew rates. The feasibility of whole-brain imaging at 1.5mm-isotropic spatial resolution was demonstrated with gradient-echo and spin-echo diffusion-weighted EPI.ResultsAs compared to a whole-body gradient coil, the EPI echo spacing in the head-only gradient coil was reduced by 48%. Simulation and in vivo results, respectively, showed up to 25-26% and 19% improvement in signal dropout. Whole-brain imaging with EPI at 1.5mm spatial resolution provided good whole-brain coverage, spatial linearity, and low spatial distortion effects.ConclusionOur results of human brain imaging with EPI using the compact head gradient coil at slew rates higher than in conventional whole-body MR systems demonstrate substantially improved image distortion, and point to a potential for benefits to non-EPI pulse sequences. J. Magn. Reson. Imaging 2016;44:653-664.