Multi-echo balanced SSFP with a sequential phase-encoding order for functional MR imaging at 7T
Multi-echo balanced SSFP with a sequential phase-encoding order for functional MR imaging at 7T
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具有连续相位编码顺序的多回波平衡 SSFP，适用于 7T 的功能性 MR 成像
DOI：
10.1002/mrm.29301
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发表时间：
2022-06-03
影响因子：
3.3
通讯作者：
Xue，Rong
中科院分区：
文献类型：
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作者：
Liang，Huilou;Pan，Ziyi;Xue，Rong
目的开发一种基于回波序列的二维多回波带通平衡SSFP序列（sequential multi-echo bSSFP），并评估其在7 T快速脑功能成像中的性能。方法由于周期性k空间调制，序列多回波bSSFP图像表现出多个重影，提出了一种基于GRAPPA的重建方法来消除重影伪影。进行MRI实验以比较多回波bSSFP和传统单回波bSSFP的图像质量。使用棋盘格视觉刺激进行亚毫米分辨率fMRI以比较多回波bSSFP、常规单回波bSSFP和标准梯度回波EPI（GE-EPI）的激活特征。结果单回波bSSFP和多回波bSSFP图像之间的平均结构相似性指数较高，回波链长度（ETL）较短。多回波bSSFP（ETL = 3）显示的时间SNR（tSNR）值高于GRAPPA加速单回波bSSFP（R= 2）。在亚毫米分辨率fMRI实验中，多回波bSSFP（ETL = 3）接近GRAPPA加速的单回波bSSFP（R= 2）的成像速度，但没有tSNR损失，并且由于加速而减少了激活。GE-EPI和多回波bSSFP（ETL = 3）之间的中值和显著激活体素的数量相当，提供了几乎无失真的功能图像，并继承了传统bSSFP.ConclusionSequential多回波bSSFP（ETL = 3）的激活模式适用于快速fMRI亚毫米平面内分辨率，并提供了一种选择，以加速bSSFP成像，而不会像并行成像一样出现tSNR损失。
PurposeTo develop a 2D multi‐echo passband balanced SSFP (bSSFP) sequence using an echo‐train readout with a sequential phase‐encoding order (sequential multi‐echo bSSFP), and evaluate its performance in fast functional brain imaging at 7 T.MethodsAs images of sequential multi‐echo bSSFP exhibit multiple ghosts due to periodic k‐space modulations, a GRAPPA‐based reconstruction method was proposed to eliminate ghosting artifacts. MRI experiments were performed to compare the image quality of multi‐echo bSSFP and conventional single‐echo bSSFP. Submillimeter‐resolution fMRI using a checkerboard visual stimulus was conducted to compare the activation characteristics of multi‐echo bSSFP, conventional single‐echo bSSFP and standard gradient‐echo EPI (GE‐EPI).ResultsA higher mean structural similarity index was found between images of single‐echo bSSFP and multi‐echo bSSFP with a shorter echo train length (ETL). Multi‐echo bSSFP (ETL = 3) showed higher temporal SNR (tSNR) values than GRAPPA‐accelerated single‐echo bSSFP (R= 2). In submillimeter‐resolution fMRI experiments, multi‐echo bSSFP (ETL = 3) approached the imaging speed of GRAPPA‐accelerated single‐echo bSSFP (R= 2), but without tSNR penalty and reduced activation due to acceleration. The mediant‐value and the number of significantly activated voxels were comparable between GE‐EPI and multi‐echo bSSFP (ETL = 3) that provides virtually distortion‐free functional images and inherits the activation patterns of conventional bSSFP.ConclusionSequential multi‐echo bSSFP (ETL = 3) is suitable for fast fMRI with submillimeter in‐plane resolution, and offers an option to accelerate bSSFP imaging without tSNR penalty like parallel imaging.