Vallée Emilie, Håberg Asta K, Kristoffersen Anders
MI Lab, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
J Magn Reson Imaging. 2014 Mar;39(3):656-64. doi: 10.1002/jmri.24190. Epub 2013 May 29.
To compare the sensitivity and specificity of three-dimensional (3D) principles of echo shifting using a train of observations (PRESTO) and passband balanced steady-state free precession (SSFP) functional MRI (fMRI) sequences combined with integrated parallel acquisition techniques (iPAT) at 3 Tesla (T).
The 3D fMRI was performed using PRESTO and passband balanced SSFP with 3 mm and 1.9 mm isotropic voxels combined with iPAT, while volunteers underwent visual stimulation. From whole-brain activation maps and predefined regions of interest in the visual cortex, Z-score distributions, percentage of fMRI signal change, and the fMRI signals' temporal profile were compared between the sequences for the two spatial resolutions to estimate sensitivity and specificity.
For PRESTO, the Z-score distributions had higher mean and maximum Z-values for both resolutions than for SSFP, and the activated voxels were located to the visual cortex with high sensitivity. For SSFP, the activation was more scattered, and voxels with the highest sensitivity were found in the draining veins. The good functional contrast in PRESTO allowed for separation of voxels with early (<5 s) and late (>5 s) signal change; thus, the signal from larger draining veins could be removed. The ensuing PRESTO activation maps represent the early fMRI signal, probably more closely related to neuronal activity.
The 3D fMRI PRESTO sequence demonstrated better sensitivity and specificity than SSFP.
比较三维（3D）回波移位原理的一系列观察（PRESTO）和带通平衡稳态自由进动（SSFP）功能磁共振成像（fMRI）序列结合集成并行采集技术（iPAT）在3特斯拉（T）场强下的敏感性和特异性。
采用PRESTO和带通平衡SSFP进行3D fMRI，体素各向同性分别为3 mm和1.9 mm，并结合iPAT，同时让志愿者接受视觉刺激。从全脑激活图和视觉皮层中预先定义的感兴趣区域，比较两种空间分辨率下各序列之间的Z分数分布、fMRI信号变化百分比以及fMRI信号的时间轮廓，以评估敏感性和特异性。
对于PRESTO，两种分辨率下的Z分数分布的平均和最大Z值均高于SSFP，且激活的体素以高敏感性定位于视觉皮层。对于SSFP，激活更为分散，在引流静脉中发现了敏感性最高的体素。PRESTO良好的功能对比度允许区分信号变化早（<5秒）和晚（>5秒）的体素；因此，可以去除来自较大引流静脉的信号。随后得到的PRESTO激活图代表了早期fMRI信号，可能与神经元活动更密切相关。
3D fMRI PRESTO序列显示出比SSFP更好的敏感性和特异性。
