Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, California, USA.
Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.
Magn Reson Med. 2017 Dec;78(6):2275-2282. doi: 10.1002/mrm.26611. Epub 2017 Feb 10.
To evaluate the feasibility of through-time spiral generalized autocalibrating partial parallel acquisition (GRAPPA) for low-latency accelerated real-time MRI of speech.
Through-time spiral GRAPPA (spiral GRAPPA), a fast linear reconstruction method, is applied to spiral (k-t) data acquired from an eight-channel custom upper-airway coil. Fully sampled data were retrospectively down-sampled to evaluate spiral GRAPPA at undersampling factors R = 2 to 6. Pseudo-golden-angle spiral acquisitions were used for prospective studies. Three subjects were imaged while performing a range of speech tasks that involved rapid articulator movements, including fluent speech and beat-boxing. Spiral GRAPPA was compared with view sharing, and a parallel imaging and compressed sensing (PI-CS) method.
Spiral GRAPPA captured spatiotemporal dynamics of vocal tract articulators at undersampling factors ≤4. Spiral GRAPPA at 18 ms/frame and 2.4 mm /pixel outperformed view sharing in depicting rapidly moving articulators. Spiral GRAPPA and PI-CS provided equivalent temporal fidelity. Reconstruction latency per frame was 14 ms for view sharing and 116 ms for spiral GRAPPA, using a single processor. Spiral GRAPPA kept up with the MRI data rate of 18ms/frame with eight processors. PI-CS required 17 minutes to reconstruct 5 seconds of dynamic data.
Spiral GRAPPA enabled 4-fold accelerated real-time MRI of speech with a low reconstruction latency. This approach is applicable to wide range of speech RT-MRI experiments that benefit from real-time feedback while visualizing rapid articulator movement. Magn Reson Med 78:2275-2282, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
评估通过时间螺旋广义自校准部分并行采集（GRAPPA）用于低延迟实时 MRI 语音的可行性。
通过时间螺旋 GRAPPA（螺旋 GRAPPA），一种快速线性重建方法，应用于从八通道定制上气道线圈采集的螺旋（k-t）数据。全采样数据被回顾性地下采样，以评估在欠采样因子 R=2 到 6 时的螺旋 GRAPPA。伪黄金角螺旋采集用于前瞻性研究。对三个被试进行成像，同时执行一系列涉及快速发音器官运动的语音任务，包括流利的语音和节拍盒。将螺旋 GRAPPA 与视图共享以及并行成像和压缩感知（PI-CS）方法进行比较。
螺旋 GRAPPA 在欠采样因子≤4 时捕获了声道发音器官的时空动态。在 18 ms/帧和 2.4 mm/pixel 下的螺旋 GRAPPA 在描绘快速运动的发音器官方面优于视图共享。螺旋 GRAPPA 和 PI-CS 提供了等效的时间保真度。使用单个处理器，每帧的重建延迟为 14 ms 用于视图共享，116 ms 用于螺旋 GRAPPA。螺旋 GRAPPA 与 MRI 数据率 18ms/帧保持同步，使用八个处理器。PI-CS 重建 5 秒动态数据需要 17 分钟。
螺旋 GRAPPA 实现了 4 倍加速的实时 MRI 语音，具有较低的重建延迟。这种方法适用于广泛的语音 RT-MRI 实验，这些实验受益于实时反馈，同时可视化快速发音器官运动。磁共振医学 78：2275-2282，2017。©2017 国际磁共振学会。
