HALF FOURIER RECONSTRUCTION OF SPIRAL MR IMAGES

简介：常规k-空间的部分采样 自旋翘曲成像已经成为减少回波时间或 总获取时间。以类似的方式，重建图像 从交错的螺旋k空间轨迹也是可能的 只获得了交错数量的一半。方法和 讨论：此方法依赖于厄米共轭对称性 原始数据，因此对影响它的因素很敏感 对称性，如B0场不均匀，B1位相变化，麦克斯韦 术语等。不幸的是，这些都是存在于 因此，在扫描仪中获取的数据的校正方法是 必填项。螺旋成像中的半傅立叶重建依赖于 将螺旋欠采样伪影以正交方式放置到所需的 已成像。不幸的是，在存在相位变化的情况下 图像对象，则这些伪像出现在距离 不均质性的位置。最简单的更正是使用 二维零差校正类似于它在 自旋翘曲半傅立叶重建，但这并不能解决 非局部化图像伪影问题。基本奈奎斯特 采样限制被违反，数据的内插需要 更优插值函数的构造 中最常用的网格化算法的准确性 螺旋图像重建。结论：这项技术适用 提高功能性磁共振成像时间分辨率的前景 使用螺旋成像序列的研究和其他研究。

Introduction: Partial sampling of k-space in conventional spin-warp imaging has become a standard way of reducing echo times or total acquisition time. In an analogous way, reconstruction of images from interleaved spiral k-space trajectories is also possible where only half the number of interleaves are acquired. Methods and Discussion: This method relies on the Hermitian conjugate symmetry of the raw data and hence is sensitive to factors influencing this symmetry, such as B0 field inhomogeneity, B1 phase variation, Maxwell terms, etc. Unfortunately, these are all factors which are present in data acquired in the scanner therefore methods of correction are required. Half Fourier reconstruction in spiral imaging relies on putting the spiral undersampling artifact in quadrature to the desired imaged. Unfortunately, in the presence of phase variations in the imaged object, these artifacts appear at some distance from the location of the inhomogeneity. The simplest correction is to use a two dimensional homodyne correction similar to the way it is used in spin warp half Fourier reconstruction but this does not solve the problem of the non-localized image artifacts. Fundamental Nyquist sampling limits are being violated and interpolation of data requires the construction of better interpolation functions bringing into question the accuracy of the gridding algorithm most commonly used in spiral image reconstruction. Conclusion: This technique holds promise for improving the temporal resolution of functional MR imaging studies and other studies employing the spiral imaging sequence.