Enhancement of temporal resolution and BOLD sensitivity in real-time fMRI using multi-slab echo-volumar imaging.
Enhancement of temporal resolution and BOLD sensitivity in real-time fMRI using multi-slab echo-volumar imaging.
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DOI：
10.1016/j.neuroimage.2012.02.059
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发表时间：
2012-05-15
期刊：
影响因子：
5.7
通讯作者：
Speck, Oliver
中科院分区：
文献类型：
--
作者：
Posse, Stefan;Ackley, Elena;Mutihac, Radu;Rick, Jochen;Shane, Matthew;Murray-Krezan, Cristina;Zaitsev, Maxim;Speck, Oliver
关键词：
在本研究中，研究人员开发了一种使用多板回声体成像（EVI）的高速功能磁共振成像新方法，该方法可以最大限度地减少几何图像失真和空间模糊，并能够对生理信号波动进行无锯齿采样，与传统的回声平面成像（EPI）相比，提高BOLD灵敏度。在配备12通道头线圈的临床3特斯拉MRI扫描仪上，使用286 ms时间分辨率（4 mm各向同性体素大小）的全脑4层EVI和136 ms时间分辨率（4×4×6 mm3体素大小）的部分脑2层EVI进行实时功能磁共振成像。与EPI相比，视觉和运动任务的四板EVI显著增加了BOLD信号幅度的平均值（视觉：96%，运动：66%）和最大值t-score（视觉：263%，运动：124%）和平均值（视觉：59%，运动：131%）和最大值（视觉：29%，运动：67%）。时域移动平均滤波（2秒宽）抑制来自心脏和呼吸波动的生理噪声，与EPI相比，进一步提高了平均（视觉：196%，运动：140%）和最大（视觉：384%，运动：200%）t得分，并增加了激活程度（视觉：73%，运动：70%）。与EPI相比，在高采样率下，仅适度降低了时间信噪比（平均：- 52%），并且在回声时域内采样BOLD效应的时间更长，因此在听觉皮层中也测量到了类似的灵敏度增强。双平板EVI进一步提高了测量任务相关激活的时间分辨率，并在5分钟扫描中实现了个体受试者的5个主要静息状态网络（rsn）的映射。双侧感觉运动、默认模式和枕部rsn在短至75秒的时间内即可检测到。综上所述，实时多板EVI的高采样率显著提高了研究血流动力学响应时间动态的灵敏度，以及在短测量时间内表征高场强下的功能网络。
In this study, a new approach to high-speed fMRI using multi-slab echo-volumar imaging (EVI) is developed that minimizes geometrical image distortion and spatial blurring, and enables nonaliased sampling of physiological signal fluctuation to increase BOLD sensitivity compared to conventional echo-planar imaging (EPI). Real-time fMRI using whole brain 4-slab EVI with 286 ms temporal resolution (4 mm isotropic voxel size) and partial brain 2-slab EVI with 136 ms temporal resolution (4×4×6 mm3 voxel size) was performed on a clinical 3 Tesla MRI scanner equipped with 12-channel head coil. Four-slab EVI of visual and motor tasks significantly increased mean (visual: 96%, motor: 66%) and maximum t-score (visual: 263%, motor: 124%) and mean (visual: 59%, motor: 131%) and maximum (visual: 29%, motor: 67%) BOLD signal amplitude compared with EPI. Time domain moving average filtering (2 s width) to suppress physiological noise from cardiac and respiratory fluctuations further improved mean (visual: 196%, motor: 140%) and maximum (visual: 384%, motor: 200%) t-scores and increased extents of activation (visual: 73%, motor: 70%) compared to EPI. Similar sensitivity enhancement, which is attributed to high sampling rate at only moderately reduced temporal signal-to-noise ratio (mean: − 52%) and longer sampling of the BOLD effect in the echo-time domain compared to EPI, was measured in auditory cortex. Two-slab EVI further improved temporal resolution for measuring task-related activation and enabled mapping of five major resting state networks (RSNs) in individual subjects in 5 min scans. The bilateral sensorimotor, the default mode and the occipital RSNs were detectable in time frames as short as 75 s. In conclusion, the high sampling rate of real-time multi-slab EVI significantly improves sensitivity for studying the temporal dynamics of hemodynamic responses and for characterizing functional networks at high field strength in short measurement times.
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