Combining multiband slice selection with consistent k-t-space EPSI for accelerated spectral imaging.
Combining multiband slice selection with consistent k-t-space EPSI for accelerated spectral imaging.
复制标题
将多波段切片选择与一致的 k-t 空间 EPSI 相结合，以实现加速光谱成像。
DOI：
10.1002/mrm.27767
复制
发表时间：
2019
影响因子：
3.3
通讯作者：
Tal,Assaf
中科院分区：
文献类型：
--
作者：
Schmidt,Rita;Seginer,Amir;Tal,Assaf
目的设计和实现一种用于快速光谱成像的多层MRSI方法，该方法使用回波平面光谱成像（EPSI）的修改版本，其提供更高的光谱宽度和/或更短的扫描时间。这通常通过分别重建“正”和“负”数据集并对两者求平均来解决。然而，每个相位编码的读出线之间的一致性可以通过将EPSI读出与交替的“blipped”相位编码梯度插入来实现。该方法将沿着时间维度的不一致性与沿着相位编码维度的不一致性交换，这是直接校正的，如在各种EPI重建方案中常规地进行的。与EPSI相比，这种一致的k-t-空间EPSI使谱宽加倍，或者在替代实现中，产生与EPSI相同的谱宽，但采集时间为一半。在这项工作中，多波段CAIPIRINHA（控制混叠在并行成像的结果在更高的加速度）切片选择集成一致的k-t-空间EPSI，以进一步加速测量2-fold.ResultsThe一致的k-t-空间EPSI的可行性证明在两个幻影和体内脑成像在3 T，和四个脉冲方案的变种进行了评估。它被证明是有用的，在优化光谱宽度和扫描加速度，这两者都是在体内的限制因素。双波段实施被证明可以缩短扫描的持续时间4-fold.ConclusionThe一致的k-t-space EPSI可以用来加速MRSI或，可选地，其频谱宽度增加一倍。添加双频CAIPIRINHA进一步将采集速度提高了2倍。
PurposeTo design and implement a multislice MRSI method for fast spectroscopic imaging, using a modified version of echo planar spectroscopic imaging (EPSI) that offers higher spectral width and/or shorter scan time.MethodsEcho planar spectroscopic imaging suffers from inconsistencies between readout lines acquired with gradients of opposite signs, which has typically been addressed by reconstructing the “positive” and “negative” data sets separately and averaging the two. Nevertheless, consistency between the readout lines of each phase encode can be achieved by interposing the EPSI readouts with alternating “blipped” phase‐encode gradients. This method exchanges inconsistencies along the temporal dimension with inconsistencies along the phase‐encode dimension, which are straightforward to correct, as is conventionally done in various EPI reconstruction schemes. Such consistent k‐t‐space EPSI doubles the spectral width in comparison to EPSI, or, in an alternative realization, yields the same spectral width as EPSI, but at half the acquisition time. In this work, multiband CAIPIRINHA (controlled aliasing in parallel imaging results in higher acceleration) slice selection was integrated with consistent k‐t‐space EPSI to further accelerate the measurement 2‐fold.ResultsThe feasibility of a consistent k‐t‐space EPSI was demonstrated in both phantoms and in vivo brain imaging at 3 T, and four pulse scheme variants were evaluated. It was demonstrated to be useful in optimizing the spectral width and scan acceleration, both of which are limiting factors in vivo. Dual‐band implementation was shown to shorten the duration of the scan 4‐fold.ConclusionThe consistent k‐t‐space EPSI can be used to accelerate MRSI or, alternatively, double its spectral width. Adding dual‐band CAIPIRINHA further accelerates the acquisition by a factor of 2.