Department of Condensed Matter Physics, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia.
Sci Rep. 2021 Jan 12;11(1):541. doi: 10.1038/s41598-020-80652-z.
In MRI, usually the Field of View (FOV) has to cover the entire object. If this condition is not fulfilled, an infolding image artifact is observed, which suppresses visualization. In this study it is shown that for samples with translational symmetry, i.e., those consisting of identical objects in periodic unit cells, the FOV can be reduced to match the unit cell which enables imaging of an average object, of which the signal is originated from all unit cells of the sample, with no punishment by a loss in signal-to-noise ratio (SNR). This theoretical prediction was confirmed by experiments on a test sample with a 7 × 7 mm unit cell arranged in a 3 × 3 matrix which was scanned by the spin-echo and by single point imaging methods. Effects of experimental imperfections in size and orientation mismatch between FOV and unit cell were studied as well. Finally, this method was demonstrated on a 3D periodic sample of tablets, which yielded well-resolved images of moisture distribution in an average tablet, while single tablet imaging provided no results. The method can be applied for SNR increase in imaging of any objects with inherently low signals provided they can be arranged in a periodic structure.
在 MRI 中，通常需要将视野 (FOV) 覆盖整个物体。如果不满足此条件，则会观察到折叠图像伪影，从而抑制可视化。在这项研究中表明，对于具有平移对称性的样本，即由周期性晶胞中相同物体组成的样本，FOV 可以减小到与晶胞匹配，从而能够对平均物体进行成像，其信号源自样本的所有晶胞，而不会因信噪比 (SNR) 损失而受到惩罚。这一理论预测通过对一个 7×7mm 晶胞组成的 3×3 矩阵的测试样本进行自旋回波和单点成像方法扫描的实验得到了证实。还研究了 FOV 和晶胞之间尺寸和方向失配的实验不完美的影响。最后，该方法在 3D 周期性片剂样品上进行了演示，该方法在平均片剂的水分分布中产生了分辨率良好的图像，而单个片剂成像则没有结果。该方法可应用于具有固有低信号的任何物体的 SNR 增加，前提是它们可以排列在周期性结构中。
