Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Maryland, Bethesda, USA.
Magn Reson Med. 2024 Jan;91(1):252-265. doi: 10.1002/mrm.29850. Epub 2023 Sep 28.
Accelerate multislice 2D MRI by using RF pulses that simultaneously act on different slices to combine contrast preparation and image acquisition.
MRI applications often require the use of multiple RF pulses to generate desired contrast and prepare the signal for readout. Examples are the use of inversion prepulses to generate T contrast, or the use of spin-echo preparations to generate T or diffusion contrast. In multislice MRI, this separation of contrast preparation and readout can render scans time-inefficient and lengthy. We introduce a class of pulse sequences that overcomes this inefficiency by combining contrast preparation and signal readout. This is accomplished by using RF pulses that manipulate the magnetization of multiple slices simultaneously and a gradient crusher scheme that selects a target slice for readout.
Feasibility of the method was demonstrated for spin echo-based measurement of water diffusion and tissue pulsation in human brain at 3 T. Increases in time-efficiency and reductions in scan time were highly dependent on specific implementation and reached as high as 25% and 53%, respectively.
A novel approach to multislice MRI is demonstrated that reduces scan time for specific applications.
通过使用同时作用于不同切片的 RF 脉冲来加速多层 2D MRI，从而将对比度准备和图像采集结合起来。
MRI 应用通常需要使用多个 RF 脉冲来产生所需的对比度，并为读出准备信号。例如，使用反转预脉冲产生 T 对比度，或使用自旋回波准备产生 T 或扩散对比度。在多层 MRI 中，对比度准备和读出的分离可能会使扫描效率低下且冗长。我们引入了一类脉冲序列，通过同时操作多个切片的磁化强度和梯度破碎机方案来克服这种效率低下的问题，该方案选择目标切片进行读出。
在 3T 下，我们用人脑的自旋回波法证明了这种方法测量水扩散和组织搏动的可行性。时间效率的提高和扫描时间的减少高度依赖于特定的实现，分别达到了 25%和 53%。
证明了一种新的多层 MRI 方法，该方法可以减少特定应用的扫描时间。
