Modeling and optimization of Look-Locker spin labeling for measuring perfusion and transit time changes in activation studies taking into account arterial blood volume
Modeling and optimization of Look-Locker spin labeling for measuring perfusion and transit time changes in activation studies taking into account arterial blood volume
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DOI：
10.1002/mrm.21442
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发表时间：
2008-02-01
影响因子：
3.3
通讯作者：
Gowland, P. A.
中科院分区：
文献类型：
--
作者：
Francis, S. T.;Bowtell, R.;Gowland, P. A.
这项工作描述了一种新的室室模型，用于looklocker （LL）血流敏感交替反转恢复（FAIR）序列的逐步时间分析，该序列将FAIR动脉自旋标记（ASL）方案与LL回声平面成像（EPI）测量相结合，使用多读数EPI序列进行同时灌注和T-2（*）测量。新模型强调了血液通过小动脉室传递时间6在灌注量化中的重要性。期望的信号以逐步的方式计算，以避免不同隔间之间的不连续。提出了在1.5 t、3 t和7T下具有高信噪比（SNR）和高时间分辨率的灌注测量的最佳LL-FAIR脉冲序列时序。与标准FAIR相比，LL-FAIR在单位时间内提供更好的信噪比。该序列已在实验中用于同时监测灌注、传递时间和T2*对视觉刺激反应的变化。结果发现，脑激活时灌注比静息状态值94 13 ml/100 g/min增加83 +/- 4%，T-2（*）增加3.5 +/- 0.5%。
This work describes a new compartmental model with stepwise temporal analysis for a Look-Locker (LL)-flow-sensitive alternating inversion-recovery (FAIR) sequence, which combines the FAIR arterial spin labeling (ASL) scheme with a LL echo planar imaging (EPI) measurement, using a multireadout EPI sequence for simultaneous perfusion and T-2(*) measurements. The new model highlights the importance of accounting for the transit time of blood through the arteriolar compartment, 6, in the quantification of perfusion. The signal expected is calculated in a step-wise manner to avoid discontinuities between different compartments. The optimal LL-FAIR pulse sequence timings for the measurement of perfusion with high signal-to-noise ratio (SNR), and high temporal resolution at 1.5, 3, and 7T are presented. LL-FAIR is shown to provide better SNR per unit time compared to standard FAIR. The sequence has been used experimentally for simultaneous monitoring of perfusion, transit time, and T2* changes in response to a visual stimulus in four subjects. It was found that perfusion increased by 83 +/- 4% on brain activation from a resting state value of 94 13 ml/100 g/min, while T-2(*) increased by 3.5 +/- 0.5%.