Chemical Physics Department, Weizmann Institute of Science, Rehovot, Israel.
Magn Reson Imaging. 2010 Jan;28(1):77-86. doi: 10.1016/j.mri.2009.05.026. Epub 2009 Jul 15.
An approach has been recently introduced for acquiring two-dimensional (2D) nuclear magnetic resonance images in a single scan, based on the spatial encoding of the spin interactions. This article explores the potential of integrating this spatial encoding together with conventional temporal encoding principles, to produce 2D single-shot images with moderate field of views. The resulting "hybrid" imaging scheme is shown to be superior to traditional schemes in non-homogeneous magnetic field environments. An enhancement of previously discussed pulse sequences is also proposed, whereby distortions affecting the image along the spatially encoded axis are eliminated. This new variant is also characterized by a refocusing of T(2)(*) effects, leading to a restoration of high-definition images for regions which would otherwise be highly dephased and thus not visible. These single-scan 2D images are characterized by improved signal-to-noise ratios and a genuine T(2) contrast, albeit not free from inhomogeneity distortions. Simple postprocessing algorithms relying on inhomogeneity phase maps of the imaged object can successfully remove most of these residual distortions. Initial results suggest that this acquisition scheme has the potential to overcome strong field inhomogeneities acting over extended acquisition durations, exceeding 100 ms for a single-shot image.
最近提出了一种在单次扫描中获取二维（2D）磁共振图像的方法，该方法基于自旋相互作用的空间编码。本文探讨了将这种空间编码与传统的时间编码原理相结合的潜力，以产生具有中等视野的 2D 单-shot 图像。结果表明，这种“混合”成像方案在非均匀磁场环境下优于传统方案。还提出了对先前讨论的脉冲序列的增强，从而消除了沿空间编码轴影响图像的失真。这种新变体的特点是 T(2)(*)效应的重新聚焦，从而为原本高度去相位且不可见的区域恢复高清晰度图像。这些单扫描 2D 图像的特点是信噪比提高，并且具有真正的 T(2)对比度，尽管不受非均匀性失真的影响。依赖于所成像物体的不均匀性相位图的简单后处理算法可以成功地去除大部分这些残余失真。初步结果表明，这种采集方案有可能克服作用于扩展采集时间的强磁场不均匀性，单次拍摄图像的采集时间超过 100ms。
