Tavallaei Mohammad Ali, Johnson Patricia M, Liu Junmin, Drangova Maria
Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario N6A 5B7, Canada and Biomedical Engineering Graduate Program, The University of Western Ontario, London, Ontario N6A 5B9, Canada.
Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario N6A 5B7, Canada and Department of Medical Biophysics, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada.
Med Phys. 2016 Jan;43(1):62. doi: 10.1118/1.4937780.
To develop and evaluate a tool for accurate, reproducible, and programmable motion control of imaging phantoms for use in motion sensitive magnetic resonance imaging (MRI) appli cations.
In this paper, the authors introduce a compact linear motion stage that is made of nonmagnetic material and is actuated with an ultrasonic motor. The stage can be positioned at arbitrary positions and orientations inside the scanner bore to move, push, or pull arbitrary phantoms. Using optical trackers, measuring microscopes, and navigators, the accuracy of the stage in motion control was evaluated. Also, the effect of the stage on image signal-to-noise ratio (SNR), artifacts, and B0 field homogeneity was evaluated.
The error of the stage in reaching fixed positions was 0.025 ± 0.021 mm. In execution of dynamic motion profiles, the worst-case normalized root mean squared error was below 7% (for frequencies below 0.33 Hz). Experiments demonstrated that the stage did not introduce artifacts nor did it degrade the image SNR. The effect of the stage on the B0 field was less than 2 ppm.
The results of the experiments indicate that the proposed system is MRI-compatible and can create reliable and reproducible motion that may be used for validation and assessment of motion related MRI applications.
开发并评估一种用于运动敏感磁共振成像（MRI）应用中成像体模的精确、可重复且可编程运动控制的工具。
在本文中，作者介绍了一种由非磁性材料制成并由超声波电机驱动的紧凑型直线运动平台。该平台可定位在扫描仪孔内的任意位置和方向，以移动、推动或拉动任意体模。使用光学跟踪器、测量显微镜和导航仪评估了该平台在运动控制方面的精度。此外，还评估了该平台对图像信噪比（SNR）、伪影和B0场均匀性的影响。
该平台到达固定位置的误差为0.025±0.021毫米。在执行动态运动曲线时，最坏情况下的归一化均方根误差低于7%（对于低于0.33赫兹的频率）。实验表明，该平台不会引入伪影，也不会降低图像SNR。该平台对B0场的影响小于2 ppm。
实验结果表明，所提出的系统与MRI兼容，能够产生可靠且可重复的运动，可用于与运动相关的MRI应用的验证和评估。
