Correction of excitation profile in Zero Echo Time (ZTE) imaging using quadratic phase-modulated RF pulse excitation and iterative reconstruction.
Correction of excitation profile in Zero Echo Time (ZTE) imaging using quadratic phase-modulated RF pulse excitation and iterative reconstruction.
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DOI：
10.1109/tmi.2014.2300500
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发表时间：
2014-04
影响因子：
10.6
通讯作者：
Wehrli FW
中科院分区：
文献类型：
--
作者：
Li C;Magland JF;Seifert AC;Wehrli FW
零回波时间(ZTE)成像是一种很有前途的短T2组织核磁共振成像(MRI)技术。该方法目前阻碍其转化到临床的固有问题是在激励期间存在空间编码梯度，这导致硬脉冲在空间上变得选择性，导致图像中的模糊和阴影伪影。虽然缩短射频(RF)脉冲持续时间可以缓解这一问题，但由此产生的射频峰值功率和比吸收率(SAR)在实践中会阻碍这种解决方案。在这项工作中，描述了一种方法，通过应用二次调相射频激励和迭代求解从中兴通讯成像的信号模型建立的反问题来纠正伪影。还开发了一种简单的脉冲序列来测量射频脉冲的激发轮廓。仿真、体模和活体实验的结果表明，该方法对纠正非均匀激励引起的图像伪影是有效的。该方法可能有助于将中兴通讯MRI建立为常规的3D脉冲序列，用于在临床扫描仪上对质子和其他具有准固态行为的核进行成像。
Zero-echo Time (ZTE) imaging is a promising technique for magnetic resonance imaging (MRI) of short-T2 tissue nuclei in tissues. A problem inherent to the method currently hindering its translation to the clinic is the presence of a spatial encoding gradient during excitation, which causes the hard pulse to become spatially selective, resulting in blurring and shadow artifacts in the image. While shortening radiofrequency (RF) pulse duration alleviates this problem the resulting elevated RF peak power and specific absorption rate (SAR) in practice impede such a solution. In this work, an approach is described to correct the artifacts by applying quadratic phase-modulated RF excitation and iteratively solving an inverse problem formulated from the signal model of ZTE imaging. A simple pulse sequence is also developed to measure the excitation profile of the RF pulse. Results from simulations, phantom and in vivo studies, demonstrate the effectiveness of the method in correcting image artifacts caused by inhomogeneous excitation. The proposed method may contribute toward establishing ZTE MRI as a routine 3D pulse sequence for imaging protons and other nuclei with quasi solid-state behavior on clinical scanners.