Transverse Relaxation Time (T2) Mapping in the Brain With Off-Resonance Correction Using Phase-Cycled Steady-State Free Precession Imaging
Transverse Relaxation Time (T2) Mapping in the Brain With Off-Resonance Correction Using Phase-Cycled Steady-State Free Precession Imaging
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DOI：
10.1002/jmri.21849
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发表时间：
2009-08-01
影响因子：
4.4
通讯作者：
Deoni, Sean C. L.
中科院分区：
文献类型：
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作者：
Deoni, Sean C. L.
目的：46 研究一种更全面地解释 DESPOT2（T-2 的驱动平衡单脉冲观测）映射技术中的非共振影响的新方法。材料和方法：DESPOT2 方法从完全平衡稳态自由进动（bSSFP）在多个翻转角上获取的图像中导出 T2 信息。非共振影响，通过 bSSFP 图像呈现为信号强度改变的带，导致相应计算图中的 T-2 值错误。射频 (RF) 相位循环，其中 RF 脉冲的相位沿着脉冲'tr,dn 递增；提供了消除这些伪影的潜在方法。在这项工作中，我们提出了一种通用方法，称为 DESPOT2，具有完整建模 (DESPOT2-FM)，用于从使用两个 RF 相位增量获取的双翻转角 bSSFP 数据导出 T-2 以及偏共振频率。结果：对该方法进行了演示。在体内，通过在 3T 下采集全脑 1 mm(3) 同位素 T-2 图谱，即使在磁化率诱导梯度陡峭的区域，也能提供近乎无伪影的图谱。结论：DESPOT2-FM 提供了一种在 3T 下高精度且无伪影地获取高空间分辨率全脑 T-2 图谱的有效方法。
Purpose: 46 investigate a new approach for more completely accounting for off-resonance affects in the DESPOT2, (driven equilibrium single pulse observation of T-2) mapping technique.Materials and,Methods:The DESPOT2 method derives T2 information, from fully balanced steady-state free precession,(bSSFP) images acquired over multiple flip angles. Off-resonanee affects, which, present as bands of altered-signal intensity through the bSSFP images, results in erroneous T-2 values in the corresponding calculated maps. Radio-frequency (RF) phase-cycling, in which the phase of the RF pulse is incremented along the pulse'tr,dn; offers a potential method for eliminating these artifacts. In this work we present a general method, refer-red to as DESPOT2, with full modeling (DESPOT2-FM), for deriving T-2, as well as off-resonance frequency, from dual flip angle bSSFP data acquired with two RF phase increments.Results: The method is demonstrated. in vivo, through the acquisition of whole-brain, 1 mm(3) isotopic T-2 maps at 3T and shown to provide near artifact-free maps, even in areas with steep susceptibility induced gradients.Conclusion: DESPOT2-FM offers an efficient method for acquiring high spatial resolution whole-brain T-2 maps, at 3T with high precision and free of artifact.