A revisit of the k-space filtering effects of magnetization-prepared 3D FLASH and balanced SSFP acquisitions: Analytical characterization of the point spread functions.
A revisit of the k-space filtering effects of magnetization-prepared 3D FLASH and balanced SSFP acquisitions: Analytical characterization of the point spread functions.
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DOI：
10.1016/j.mri.2022.01.015
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发表时间：
2022-05
影响因子：
2.5
通讯作者：
Qin Q
中科院分区：
文献类型：
--
作者：
Zhu D;Qin Q
3D FLASH和平衡SSFP（bSSFP）越来越多地用于造影剂制备后的定量MRI。采集的k空间数据通过T1弛豫（或bSSFP的附加T2）进行调制。三个单独的序列参数，包括相位编码步骤的数量每次拍摄（N），翻转角（FA），和TR的快速梯度回波（GRE）成像的瞬态难以分析和优化。在这里，我们的目的是分析表征的k空间滤波效果的磁化制备的FLASH和bSSFP与点扩散函数（PSF）。幅度效应的特征在于PSF的峰值幅度，即PSF（0），由于它们从GRE采集的瞬态接近稳态，其服从与准备的纵向磁化（Mprep）的线性（具有斜率和截距，而不是成比例）关系。模糊效果由点扩展函数的半高宽表征。磁化制备的采集相关图像对比度效率的特征在于每单位时间的相对对比度噪声比（CNR）（ruCNR）。PSF（0）的斜率表征不同Mprep水平之间的相对对比度。PSF（0）的截距可能导致磁化准备成像的量化偏倚。FLASH和bSSFP经历非常小的模糊效应，这与传统的快速自旋回波（FSE）相反。提供了N、FA和TR的分析选择，以针对不同情况优化ruCNR。的FLASH和bSSFP收购的PSF的解析推导和数值验证，并与FSE收购相比，从而提供了一个有用的工具，用于优化磁化准备GRE收购。
3D FLASH and balanced SSFP (bSSFP) are increasingly used in quantitative MRI after contrast preparation. The acquired k-space data are modulated by T1 relaxation (or additional T2 for bSSFP). Three separate sequence parameters including the number of phase-encoding steps per shot (N), flip angle (FA), and TR have made the transient state of rapid gradient echo (GRE) imaging difficult for analysis and optimization. Here we aim to analytically characterize the k-space filtering effect of magnetization-prepared FLASH and bSSFP with the point spread functions (PSF). The amplitude effect is characterized with the peak magnitude of the PSF, i.e. PSF(0), which, due to their approaching from transient state to steady-state for the GRE acquisitions, obeys a linear (with a slope and an intercept, not proportional) relationship with the prepared longitudinal magnetization (Mprep). The blurring effect is characterized by the FWHM of the PSF. The magnetization-prepared acquisition-dependent image contrast efficiency is characterized with the relative contrast-to-noise ratio (CNR) per unit time (ruCNR). The slope of PSF(0) characterizes the relative contrast between different Mprep levels. The intercept of PSF(0) could lead to quantification bias for magnetization-prepared imaging. FLASH and bSSFP experience very little blurring effect, which is to the contrary of conventional fast spin echo (FSE). Analytical selections of N, FA, and TR are provided to optimize ruCNR for different scenarios. PSFs of the FLASH and bSSFP acquisitions are analytically derived and numerically validated, and compared with the FSE acquisition, thus providing a useful tool for optimizing magnetization-prepared GRE acquisitions.
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DOI：
10.1002/jmri.1880010108
发表时间：
1991-01-01
期刊：
JMRI-JOURNAL OF MAGNETIC RESONANCE IMAGING
影响因子：
--
作者：
CHIEN, D;ATKINSON, DJ;EDELMAN, RR
通讯作者：
EDELMAN, RR
影响因子：
3.3
作者：
O'Halloran, R. L.;Aksoy, M.;Bammer, R.
通讯作者：
Bammer, R.
影响因子：
19.7
作者：
Campbell-Washburn, Adrienne E.;Ramasawmy, Rajiv;Balaban, Robert S.
通讯作者：
Balaban, Robert S.
影响因子：
3.3
作者：
Cukur T;Lee JH;Bangerter NK;Hargreaves BA;Nishimura DG
通讯作者：
Nishimura DG
影响因子：
2.5
作者：
Cronin MJ;Xu J;Bagnato F;Gochberg DF;Gore JC;Dortch RD
通讯作者：
Dortch RD