Objective

The slow spatial encoding of MRI has precluded its application to rapid physiologic motion in the past. The purpose of this study is to introduce a new fast acquisition method and to demonstrate feasibility of encoding rapid two-dimensional motion of human vocal folds with sub-millisecond resolution.

Method

In our previous work, we achieved high temporal resolution by applying a rapidly switched phase encoding gradient along the direction of motion. In this work, we extend phase encoding to the second image direction by using single-point imaging with rapid encoding (SPIRE) to image the two-dimensional vocal fold oscillation in the coronal view. Image data were gated using electroglottography (EGG) and motion corrected. An iterative reconstruction with a total variation (TV) constraint was used and the sequence was also simulated using a motion phantom.

Results

Dynamic images of the vocal folds during phonation at pitches of 150 and 165 Hz were acquired in two volunteers and the periodic motion of the vocal folds at a temporal resolution of about 600 µs was shown. The simulations emphasize the necessity of SPIRE for two-dimensional motion encoding.

Discussion

SPIRE is a new MRI method to image rapidly oscillating structures and for the first time provides dynamic images of the vocal folds oscillations in the coronal plane.

中文翻译：

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使用快速编码的单点成像对声带振荡进行亚毫秒级 2D MRI

客观的

过去，MRI 的慢速空间编码排除了其在快速生理运动中的应用。本研究的目的是介绍一种新的快速采集方法，并证明以亚毫秒分辨率对人类声带快速二维运动进行编码的可行性。

方法

在我们之前的工作中，我们通过沿运动方向应用快速切换的相位编码梯度来实现高时间分辨率。在这项工作中，我们通过使用带快速编码的单点成像 (SPIRE) 将相位编码扩展到第二个图像方向，以对冠状视图中的二维声带振荡进行成像。使用电声门 (EGG) 对图像数据进行门控并进行运动校正。使用了具有总变异 (TV) 约束的迭代重建，并且还使用运动体模模拟了序列。

结果

在两名志愿者中获得了在 150 和 165 Hz 音调下发声期间声带的动态图像，并显示了时间分辨率约为 600 µs 的声带的周期性运动。模拟强调了 SPIRE 对二维运动编码的必要性。

讨论

SPIRE 是一种新的 MRI 方法，用于对快速振荡的结构进行成像，并首次提供了冠状平面中声带振荡的动态图像。