Volumetric R2* Mapping Using Z-shim Multi-Echo Gradient Echo Imaging
Volumetric R2* Mapping Using Z-shim Multi-Echo Gradient Echo Imaging
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DOI：
10.1002/mrm.25206
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发表时间：
2015-03-01
影响因子：
3.3
通讯作者：
Kim, Dong-Hyun
中科院分区：
文献类型：
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作者：
Han, Dongyeob;Nam, Yoonho;Kim, Dong-Hyun
目的介绍宏观B-0场不稳定性补偿的容积R-2* 标测方法和三维（3D）z-shim多回波采集方法。在每个负读出梯度瓣之前应用恒定值的z匀场梯度。基于该脉冲序列提出了一种相位合成算法，该算法获得了B-0抗扰度补偿场图，该场图对精确的R-2* 映射起着至关重要的作用。一个修改后的信号模型的基础上，最近建议的3D采集模型提出了R-2* quantitation.ResultsTo验证所提出的方法，幻影和体内实验的性能，并与其他方法进行比较。在体模结果中显示了场不均匀性校正范围的增加。对于在体内的研究，所提出的方法表现出增强的R-2* 地图的质量为不同的subjects.ConclusionThe所提出的方法提高了R-2* 估计，特别是在额叶和颞叶区域。Magn Reson Med 73：1164-1170，2015年。(c)2014 Wiley Periodicals，Inc.
PurposeTo introduce macroscopic B-0 field inhomogeneity-compensated volumetric R-2* mapping method with a three-dimensional (3D) z-shim multi-echo acquisition.MethodsThe proposed z-shim sequence acquired conventional and z-shimmed echoes alternately with bipolar readout gradients. A constant-valued z-shim gradient was applied prior to each negative readout gradient lobe. A phase combination algorithm was also proposed based on this pulse sequence, which acquires a B-0 inhomogeneity-compensated field map that was shown to play a critical role for accurate R-2* mapping. A modified signal model based on recently suggested model for 3D acquisition was proposed for R-2* quantification.ResultsTo validate the performance of the proposed method, phantom and in vivo experiments were performed and compared with other methods. An increase in the range of field inhomogeneity correction was shown in the phantom results. For in vivo studies, the proposed method showed enhanced R-2* map quality for the different subjects.ConclusionThe proposed method improves R-2* estimation, especially in the frontal and temporal regions. Magn Reson Med 73:1164-1170, 2015. (c) 2014 Wiley Periodicals, Inc.