K空间填充策略对基于FLASH序列的APT图像脂肪伪影的影响

doi:10.11938/cjmr20243113

摘要/Abstract

摘要：

在化学交换饱和转移（CEST）成像实验中，由于信号采集过程中纵向磁化矢量的弛豫恢复，实际采集信号的CEST对比度呈持续衰减状态，因此，CEST分段饱和模式以及对应的K空间填充方法会对CEST的图像质量和定量结果产生不同的影响. 本文通过仿真和人体实验，探究了快速小角度激发（FLASH）序列中不同K空间填充策略对颅脑酰胺质子转移（APT）成像质量以及APT对比度的影响. 研究结果显示，采用分段饱和与重排优化K空间中心优先填充技术，可有效消除皮下脂肪导致的伪影，并提高APT非对称分析获取非对称性磁化转移率MTR_asym的准确性.

关键词: 磁共振成像（MRI）, 化学交换饱和转移（CEST）, 脂肪伪影, 分段采集, K空间重排

Abstract:

In chemical exchange saturation transfer (CEST) imaging, the relaxation recovery of longitudinal magnetization during the signal acquisition process results in a decrease in CEST contrast. Consequently, the CEST saturation mode and the corresponding K-space filling method significantly influence both the image quality and quantitative results of CEST. In this paper, simulations and human experiments were conducted to examine the impact of various K-space filling strategies within the fast low angle shot (FLASH) sequence on the quality of brain amide proton transfer (APT) images and on the quantitative analysis of magnetization transfer ratio asymmetry (MTR_asym). The result indicates that employing segmented saturation techniques with optimized reordered center-out K-space filling technology can effectively mitigate artifacts caused by scalp fat and enhance the accuracy of MTR_asym values.

Key words: magnetic resonance imaging (MRI), chemical exchange saturation transfer (CEST), fat artifact, segmented acquisition, K-space reordering

中图分类号:

O482.53

逄奇凡, 王志超, 武玉朋, 李建奇. K空间填充策略对基于FLASH序列的APT图像脂肪伪影的影响[J]. 波谱学杂志, 2024, 41(4): 443-453.

PANG Qifan, WANG Zhichao, WU Yupeng, LI Jianqi. The Impact of K-Space Filling Strategy on Fat Artifacts in APT Imaging Based on FLASH Sequence[J]. Chinese Journal of Magnetic Resonance, 2024, 41(4): 443-453.

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	质子密度	T₁/ms	T₂^*/ms	饱和幅度/%
皮下脂肪（δ -3.5）	91.1%	382	68	80
大脑白质（δ 3.5）	68.6%	1087	56	10

K空间相位编码顺序	单次饱和与顺序采集	单次饱和与中心优先采集	分段饱和与顺序采集	分段饱和与中心优先采集	分段饱和与重排中心优先采集
1	1	127	#1-1	#4-31	#3-32
2	2	125	#1-2	#4-29	#1-32
:	:	:	:	:	:
16	16	97	#1-16	#4-1	#1-25
17	17	95	#1-17	#3-31	#3-24
:	:	:	:	:	:
32	32	65	#1-32	#3-1	#1-17
33	33	63	#2-1	#2-31	#3-16
:	:	:	:	:	:
48	48	33	#2-16	#2-1	#1-9
49	49	31	#2-17	#1-31	#3-8
:	:	:	:	:	:
63	63	3	#2-31	#1-3	#3-1
64	64	1	#2-32	#1-1	#1-1
65	65	2	#3-1	#1-2	#2-1
66	66	4	#3-2	#1-4	#4-1
:	:	:	:	:	:
80	80	32	#3-16	#1-32	#4-8
81	81	34	#3-17	#2-2	#2-9
:	:	:	:	:	:
96	96	64	#3-32	#2-32	#4-16
97	97	66	#4-1	#3-2	#2-17
:	:	:	:	:	:
112	112	96	#4-16	#3-32	#4-24
113	113	98	#4-17	#4-2	#2-25
:	:	:	:	:	:
127	127	126	#4-31	#4-30	#2-32
128	128	128	#4-32	#4-32	#4-32