van Osch Matthias J P, Hendrikse Jeroen, van der Grond Jeroen
Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
J Magn Reson Imaging. 2007 Jan;25(1):215-21. doi: 10.1002/jmri.20823.
To study the sensitivity for detection of activation for multiple vs. single inversion time (TI) pulsed arterial spin labeling (PASL).
The number of activated voxels and the mean t-statistic over activated voxels was measured by means of multiple and single TI PASL sequences in five volunteers during visual stimulation by means of an alternating checkerboard. Acquisition was performed by means of the transfer insensitive labeling technique (TILT) and TURBO-TILT.
It was found that the sensitivity for the detection of activation was lower for an individual TI out of a multiple TI sequence than for the corresponding single TI acquisition of equal duration. After averaging over all TIs between and including 600 and 1400 msec, the number of activated voxels and mean t-statistic were no longer statistically lower for the multiple TI sequence than for the single TI experiment.
Multiple TI PASL can be used for functional MRI (fMRI) studies, when performing the detection of activated brain regions on data that is averaged over all TIs between 600 and 1400 msec. Subsequently the multi-TI data can be used to quantify cerebral blood flow (CBF) changes upon activation. Additionally, we have shown that single TI PASL fMRI overestimates the CBF changes upon activation due to transit time changes.
研究多反转时间（TI）与单反转时间脉冲动脉自旋标记（PASL）检测激活的敏感性。
在5名志愿者通过交替棋盘格进行视觉刺激期间，采用多TI和单TI PASL序列测量激活体素的数量以及激活体素上的平均t统计量。采集通过转移不敏感标记技术（TILT）和TURBO-TILT进行。
发现多TI序列中单个TI检测激活的敏感性低于等时长的相应单TI采集。在对600至1400毫秒之间（包括600和1400毫秒）的所有TI进行平均后，多TI序列的激活体素数量和平均t统计量在统计学上不再低于单TI实验。
当对600至1400毫秒之间所有TI的数据进行平均以检测激活的脑区时，多TI PASL可用于功能磁共振成像（fMRI）研究。随后，多TI数据可用于量化激活时的脑血流量（CBF）变化。此外，我们已经表明，单TI PASL fMRI由于通过时间变化而高估了激活时的CBF变化。
