Hargreaves Brian A, Vasanawala Shreyas S, Nayak Krishna S, Hu Bob S, Nishimura Dwight G
Department of Electrical Engineering, Stanford University, Stanford, California 94305-9510, USA.
Magn Reson Med. 2003 Jul;50(1):210-3. doi: 10.1002/mrm.10488.
Fully refocused steady-state free precession (SSFP) is a rapid, efficient imaging sequence that can provide diagnostically useful image contrast. In SSFP, the signal is refocused midway between excitation pulses, much like in a spin-echo experiment. However, in SSFP, the phase of the refocused spins alternates for each resonant frequency interval equal to the reciprocal of the sequence repetition time (TR). Appropriate selection of the TR results in a 180 degrees phase difference between lipid and water signals. This phase difference can be used for fat-water separation in SSFP without any increase in scan time. The technique is shown to produce excellent non-contrast-enhanced, flow-independent angiograms of the peripheral vasculature.
完全重聚焦稳态自由进动（SSFP）是一种快速、高效的成像序列，可提供具有诊断价值的图像对比度。在SSFP中，信号在激发脉冲之间的中途被重聚焦，这与自旋回波实验非常相似。然而，在SSFP中，对于每个等于序列重复时间（TR）倒数的共振频率间隔，重聚焦自旋的相位会交替变化。适当选择TR会导致脂质和水信号之间产生180度的相位差。该相位差可用于SSFP中的脂肪-水分离，而无需增加扫描时间。结果表明，该技术可产生外周血管系统出色的非增强对比、不依赖血流的血管造影图像。
