Single-shot interleaved Z-shim EPI with optimized compensation for signal losses due to susceptibility-induced field inhomogeneity at 3 T
Single-shot interleaved Z-shim EPI with optimized compensation for signal losses due to susceptibility-induced field inhomogeneity at 3 T
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DOI：
10.1006/nimg.2002.1274
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发表时间：
2002-11-01
期刊：
影响因子：
5.7
通讯作者：
Yang, YH
中科院分区：
文献类型：
--
作者：
Gu, H;Feng, HH;Yang, YH
提出了一种新的单发回波平面成像（EPI）序列，该序列具有交错的z-shim，并对敏感信号损失进行了优化补偿。人类大脑实验表明，新方法能够恢复具有严重敏感性局部梯度的大脑区域的信号缺失，而其图像采集速度与传统的单次EPI技术相当。与传统EPI相比，新技术显著改善了前额叶腹侧和外侧颞叶的信噪比。通过放置在头部左侧的一个小钆（Gd）掺杂瓶，在左侧感觉运动皮层附近故意引入局部梯度，进行双侧手指敲击任务的脑激活实验。功能实验结果表明，交错的z-shim EPI序列有效地恢复了gd掺杂瓶造成的信号损失，并可靠地检测到双侧感觉运动区域的激活信号，而传统的EPI技术中左侧的激活信号明显减少。该新技术具有减少敏感性伪影和快速扫描速度的特点，可能特别适用于在神经精神病学研究中具有重要意义的脑基底区事件相关功能MRI实验。(C) 2002 Elsevier Science （USA）。
A new single-shot echo-planar imaging (EPI) sequence with interleaved z-shim and optimized compensation for susceptibility-induced signal loss is proposed in this paper. Experiments on human brain demonstrated that the new method is able to regain signal dropout in brain areas with severe susceptibility-induced local gradients, while its image acquisition speed is comparable to that of conventional single-shot EPI techniques. Significant signal-to-noise ratio improvements were demonstrated in the ventral prefrontal and lateral temporal lobes with the new technique compared to a conventional EPI. Brain activation experiments with a bilateral finger-tapping task were performed with intentionally introduced local gradients near the left sensorimotor cortex, by a small gadolinium (Gd)-doped bottle placed on the left side of the head. The results of the functional experiments showed that the interleaved z-shim EPI sequence effectively recovered the signal loss caused by the Gd-doped bottle and reliably detected activation signals in bilateral sensorimotor regions, while the activation signals on the left side diminished considerably in a conventional EPI technique. The new technique, with the capability of reducing susceptibility artifacts and rapid scanning speed, may be particularly useful for event-related functional MRI experiments in the base of the brain, which are of great importance in neuropsychiatric studies. (C) 2002 Elsevier Science (USA).