A rapid and robust gradient measurement technique using dynamic single-point imaging.
A rapid and robust gradient measurement technique using dynamic single-point imaging.
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DOI：
10.1002/mrm.26481
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发表时间：
2017-09
影响因子：
3.3
通讯作者：
McMillan AB
中科院分区：
文献类型：
--
作者：
Jang H;McMillan AB
提出了一种新的基于动态单点成像(SPI)的梯度测量技术，该技术可以简单、快速和稳健地测量k-空间轨迹。为了实现梯度测量，我们利用了动态SPI的可变视场(FOV)特性，该特性依赖于梯度形状。首先，从目标梯度轴获取一维动态SPI数据，然后找出不同编码时间下一维图像或k空间之间的相对视场缩放因子。这些相对比例因子是可用于图像重建的相对k空间位置。梯度测量技术也可以用来估计梯度脉冲响应函数，以作为线性时不变系统进行可重复的梯度估计。在三维超短回波、二维螺旋和多回波双极梯度回波笛卡尔成像中，提出的测量技术被用于改善重建图像质量。在多回波双极梯度回波成像中，k空间轨迹的测量允许使用斜坡采样轨迹来提高采集速度(约30%)，并在模体中更准确地定量分离脂肪和水分。所提出的基于动态SPI的方法能够以简单的实现方式快速测量k空间轨迹，并且不需要额外的硬件来改善图像质量。
We propose a new gradient measurement technique based on dynamic single point imaging (SPI), which allows simple, rapid, and robust measurement of k-space trajectory. To enable gradient measurement, we utilize the variable field of view (FOV) property of dynamic SPI which is dependent on gradient shape. First, 1D dynamic SPI data are acquired from a targeted gradient axis, and then relative FOV scaling factors between 1D images or k-spaces at varying encoding times are found. These relative scaling factors are the relative k-space position that can be used for image reconstruction. The gradient measurement technique can also be used to estimate the gradient impulse response function for reproducible gradient estimation as a linear-time invariant system. The proposed measurement technique was used to improve reconstructed image quality in 3D ultra-short echo, 2D spiral, and multi-echo bipolar gradient echo Cartesian imaging. In multi-echo bipolar gradient echo imaging, measurement of the k-space trajectory allowed the use of a ramp-sampled trajectory for improved acquisition speed (approximately 30%) and more accurate quantitative fat and water separation in a phantom. The proposed dynamic SPI-based method allows fast k-space trajectory measurement with a simple implementation and no additional hardware for improved image quality.