Moriguchi H, Wendt M, Duerk J L
Departments of Radiology and Biomedical Engineering, University Hospitals of Cleveland, Cleveland, Ohio 44106, USA.
Magn Reson Med. 2000 Nov;44(5):766-81. doi: 10.1002/1522-2594(200011)44:5<766::aid-mrm15>3.0.co;2-c.
Various kinds of nonrectilinear Cartesian k-space trajectories have been studied, such as spiral, circular, and rosette trajectories. Although the nonrectilinear Cartesian sampling techniques generally have the advantage of fast data acquisition, the gridding process prior to 2D-FFT image reconstruction usually requires a number of additional calculations, thus necessitating an increase in the computation time. Further, the reconstructed image often exhibits artifacts resulting from both the k-space sampling pattern and the gridding procedure. To date, it has been demonstrated in only a few studies that the special geometric sampling patterns of certain specific trajectories facilitate fast image reconstruction. In other words, the inherent link among the trajectory, the sampling scheme, and the associated complexity of the regridding/reconstruction process has been investigated to only a limited extent. In this study, it is demonstrated that a Lissajous trajectory has the special geometric characteristics necessary for rapid reconstruction of nonrectilinear Cartesian k-space trajectories with constant sampling time intervals. Because of the applicability of a uniform resampling (URS) algorithm, a high-quality reconstructed image is obtained in a short reconstruction time when compared to other gridding algorithms.
人们已经研究了各种非直线笛卡尔k空间轨迹，如螺旋轨迹、圆形轨迹和玫瑰花结轨迹。尽管非直线笛卡尔采样技术通常具有快速数据采集的优势，但在二维快速傅里叶变换（2D-FFT）图像重建之前的网格化过程通常需要大量额外计算，因此需要增加计算时间。此外，重建图像常常会出现由k空间采样模式和网格化过程导致的伪影。迄今为止，仅有少数研究表明某些特定轨迹的特殊几何采样模式有助于快速图像重建。换句话说，轨迹、采样方案以及重新网格化/重建过程的相关复杂性之间的内在联系仅在有限程度上得到了研究。在本研究中，证明了李萨如轨迹具有以恒定采样时间间隔快速重建非直线笛卡尔k空间轨迹所需的特殊几何特征。由于均匀重采样（URS）算法的适用性，与其他网格化算法相比，在短重建时间内即可获得高质量的重建图像。
