Lin Hung-Yu, Dale Brian M, Flask Chris A, Duerk Jeffrey L
Department of Radiology, University Hospitals of Cleveland and Case Western Reserve University, Cleveland, OH 44106, USA.
J Magn Reson Imaging. 2006 Sep;24(3):701-7. doi: 10.1002/jmri.20657.
To investigate a rapid flow-suppression method for improving the contrast-to-noise ratio (CNR) between the vessel wall and the lumen for cardiovascular imaging applications.
In this study a new dark-blood steady-state free precession (SSFP) sequence utilizing two excitation pulses per TR was developed. The first pulse is applied immediately adjacent to the slice of interest, while the second is a conventional slice-selective pulse designed to excite an SSFP signal for the static spins in the slice of interest. The slice-selective pulse is followed by fully refocused gradients along all three imaging axes over each TR. The signal amplitude (SA) from the moving spins excited by the "saturation" pulse is attenuated since they are not fully refocused at the TE.
This work provides confirmation, by both simulation and experiments, that modest adaptations of the basic True-FISP structure can limit unwanted "bright blood" signal within the vessels while simultaneously preserving the contrast and speed advantages of this well-established rapid imaging method.
Animal imaging trials confirm that dark-blood contrast is achieved with the BASS sequence, which substantially reverses the lumen-to-muscle CNR of a conventional True-FISP "bright blood" acquisition from 14.77 (bright blood) to -13.96 (dark blood) with a modest increase (24.2% of regular TR of SSFP for this implementation) in acquisition time to accommodate the additional slab-selective excitation pulse and gradient pulses.
研究一种快速血流抑制方法，以提高心血管成像中血管壁与管腔之间的对比度噪声比（CNR）。
在本研究中，开发了一种新的暗血稳态自由进动（SSFP）序列，每个TR使用两个激发脉冲。第一个脉冲紧邻感兴趣的层面施加，而第二个是传统的层面选择脉冲，旨在为感兴趣层面的静态自旋激发SSFP信号。层面选择脉冲之后，在每个TR期间沿所有三个成像轴施加完全重聚焦梯度。由“饱和”脉冲激发的移动自旋的信号幅度（SA）会衰减，因为它们在TE时未完全重聚焦。
这项工作通过模拟和实验证实，对基本True-FISP结构进行适度调整可以限制血管内不需要的“亮血”信号，同时保留这种成熟的快速成像方法的对比度和速度优势。
动物成像试验证实，使用BASS序列可实现暗血对比度，这显著逆转了传统True-FISP“亮血”采集的管腔与肌肉的CNR，从14.77（亮血）变为-13.96（暗血），采集时间适度增加（对于此实现方式，为SSFP常规TR的24.2%），以适应额外的层面选择激发脉冲和梯度脉冲。
