Rapid and motion-robust volume coverage using cross-sectional real-time MRI
Rapid and motion-robust volume coverage using cross-sectional real-time MRI
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DOI：
10.1002/mrm.28029
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发表时间：
2020-05-01
影响因子：
3.3
通讯作者：
Frahm, Jens
中科院分区：
文献类型：
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作者：
Voit, Dirk;Kalentev, Oleksandr;Frahm, Jens
目的：开发一种快速、稳健的体积磁共振成像技术，该技术基于具有自动推进切片位置的横断面实时MRI采集。方法：使用高度欠采样的径向梯度回波序列，提供自旋密度、T-1或T-2/T-1对比度，进行逐帧移动横断面的实时MRI。序列图像和线圈敏感度图的联合重建是通过对前一层进行正则化的非线性反演来完成的，这与动态实时磁共振成像是完全相同的。将每个帧移动区段厚度的20%到25%可确保连续区段的75%到80%重叠。40到67ms的采集时间允许每秒15到25个截面的速率，而体积则由截面数量乘以截面移位来定义。结果：3T的初步实现包括对人脑、颈动脉、肝脏和前列腺的研究。通常，以0.8到1.2 mm的面内分辨率、4到6 mm的截面厚度和0.8到1.5 mm的截面偏移来覆盖90到180 mm的体积，可以在4到6秒的总测量时间和15到37.5 mm/秒的截面速度内完成。然而，时空分辨率、对比度，包括脂肪饱和度和总测量时间等选项是高度可变的，可能会根据临床需要进行调整。体积测量应用前景广阔，从胎儿MRI到动态对比度增强MRI。结论：提出的方法可以在各种成像场景中实现快速和运动稳健的体积覆盖。
Purpose: To develop a rapid and motion-robust technique for volumetric MRI, which is based on cross-sectional real-time MRI acquisitions with automatic advancement of the slice position.Methods: Real-time MRI with a frame-by-frame moving cross-section is performed with use of highly undersampled radial gradient-echo sequences offering spin density, T-1, or T-2/T-1 contrast. Joint reconstructions of serial images and coil sensitivity maps from spatially overlapping sections are accomplished by nonlinear inversion with regularization to the preceding section-formally identical to dynamic real-time MRI. Shifting each frame by 20% to 25% of the section thickness ensures 75% to 80% overlap of successive sections. Acquisition times of 40 to 67 ms allow for rates of 15 to 25 sections per second, while volumes are defined by the number of cross-sections times the section shift.Results: Preliminary realizations at 3T comprise studies of the human brain, carotid arteries, liver, and prostate. Typically, coverage of a 90- to 180-mm volume at 0.8- to 1.2-mm in-plane resolution, 4- to 6-mm section thickness, and 0.8- to 1.5-mm section shift is accomplished within total measuring times of 4 to 6 seconds and a section speed of 15 to 37.5 mm per second. However, spatiotemporal resolution, contrast including options such as fat saturation and total measuring time are highly variable and may be adjusted to clinical needs. Promising volumetric applications range from fetal MRI to dynamic contrast-enhanced MRI.Conclusion: The proposed method allows for rapid and motion-robust volume coverage in a variety of imaging scenarios.