Three-dimensional echo-shifted EPI with simultaneous blip-up and blip-down acquisitions for correcting geometric distortion.
Three-dimensional echo-shifted EPI with simultaneous blip-up and blip-down acquisitions for correcting geometric distortion.
复制标题
三维回波位移 EPI，同时进行 blip-up 和 blip-down 采集，以校正几何失真。
DOI：
10.1002/mrm.29828
复制
发表时间：
2023
影响因子：
3.3
通讯作者：
Zhou,XiaohongJoe
中科院分区：
文献类型：
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作者：
Sun,Kaibao;Chen,Zhifeng;Dan,Guangyu;Luo,Qingfei;Yan,Lirong;Liu,Feng;Zhou,XiaohongJoe
目的通过使用具有相反相位编码梯度的两个读出序列，具有向上/向下闪烁采集（BUDA）的EPI可以提供高质量的图像，且失真最小。由于需要两次单独的采集，与单次激发EPI相比，BUDA使扫描时间加倍，并降低了时间分辨率，这对许多应用，特别是fMRI，提出了一个重大挑战。本研究旨在通过开发回波移位EPI BUDA（esEPI‐BUDA）技术来克服这一挑战，以在单次激发中获得blip‐up和blip‐down数据集。这些读出序列产生了一对k空间数据集，其k空间轨迹与相反的相位编码梯度方向交织。使用3D SENSE算法分别重建两个k空间数据集，从中使用FSL中的TOPUP导出时间分辨B 0场图，然后输入到联合并行成像重建的前向模型中以校正几何失真。此外，Hankel结构的低秩约束被纳入重建框架，以改善图像质量，通过减轻两个交错的k空间datasets.ResultsThe 3D esEPI-BUDA技术之间的相位误差被证明在一个幻影和健康人类受试者的fMRI研究。在体模和人脑图像中有效地校正了几何失真。在功能磁共振成像研究中，视觉激活量和BOLD响应与传统的3D回波平面images.ConclusionThe提高成像效率和动态失真校正能力提供的3D esEPI-BUDA预计将有利于许多EPI应用。
PurposeEPI with blip‐up/down acquisition (BUDA) can provide high‐quality images with minimal distortions by using two readout trains with opposing phase‐encoding gradients. Because of the need for two separate acquisitions, BUDA doubles the scan time and degrades the temporal resolution when compared to single‐shot EPI, presenting a major challenge for many applications, particularly fMRI. This study aims at overcoming this challenge by developing an echo‐shifted EPI BUDA (esEPI‐BUDA) technique to acquire both blip‐up and blip‐down datasets in a single shot.MethodsA 3D esEPI‐BUDA pulse sequence was designed by using an echo‐shifting strategy to produce two EPI readout trains. These readout trains produced a pair of k‐space datasets whose k‐space trajectories were interleaved with opposite phase‐encoding gradient directions. The two k‐space datasets were separately reconstructed using a 3D SENSE algorithm, from which time‐resolvedB0‐field maps were derived using TOPUP in FSL and then input into a forward model of joint parallel imaging reconstruction to correct for geometric distortion. In addition, Hankel structured low‐rank constraint was incorporated into the reconstruction framework to improve image quality by mitigating the phase errors between the two interleaved k‐space datasets.ResultsThe 3D esEPI‐BUDA technique was demonstrated in a phantom and an fMRI study on healthy human subjects. Geometric distortions were effectively corrected in both phantom and human brain images. In the fMRI study, the visual activation volumes and their BOLD responses were comparable to those from conventional 3D echo‐planar images.ConclusionThe improved imaging efficiency and dynamic distortion correction capability afforded by 3D esEPI‐BUDA are expected to benefit many EPI applications.