Schepers Janneke, Van Osch Matthias J P, Nicolay Klaas
Department of Experimental in vivo NMR, Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands.
Magn Reson Med. 2003 Sep;50(3):608-13. doi: 10.1002/mrm.10571.
Flow-sensitive alternating inversion recovery (FAIR) perfusion imaging suffers from high vascular signal, resulting in artifacts and overestimation of perfusion. With TurboFLASH acquisition, crushing of vascular signal by bipolar gradients after each excitation is difficult due to the requirement of an ultrashort repetition time. Therefore, insertion of a preparation phase in the FAIR sequence, after labeling and prior to TurboFLASH acquisition, is proposed. A segmented adiabatic BIR-4 pulse, interleaved with crusher gradients, was used for flow crushing. The effect of the crusher preparation is shown as a function of crusher strength for a flow phantom and in rat brain. Influence of crusher strength on the time-dependent FAIR signal from rat brain was also measured. Signal from flowing spins in a flow phantom and from arterial spins in rat brain was significantly suppressed. Image quality was improved and the overestimation of perfusion at short inflow times was eliminated.
血流敏感交替反转恢复（FAIR）灌注成像存在高血管信号问题，会导致伪影并高估灌注。采用快速成像稳态进动序列（TurboFLASH）采集时，由于需要极短的重复时间，每次激发后用双极梯度消除血管信号很困难。因此，建议在FAIR序列中，在标记后且在TurboFLASH采集之前插入一个准备阶段。使用一个分段绝热BIR-4脉冲，并与消除梯度交错，用于血流消除。在血流模型和大鼠脑中，展示了消除准备的效果与消除强度的函数关系。还测量了消除强度对大鼠脑随时间变化的FAIR信号的影响。血流模型中流动自旋的信号以及大鼠脑动脉自旋的信号被显著抑制。图像质量得到改善，短流入时间时灌注的高估现象得以消除。
