Department of Radiology, University Clinic, University of Würzburg, Würzburg, Germany.
PLoS One. 2013 Sep 10;8(9):e74501. doi: 10.1371/journal.pone.0074501. eCollection 2013.
Functional magnetic resonance imaging (fMRI) has become a powerful and influential method to non-invasively study neuronal brain activity. For this purpose, the blood oxygenation level-dependent (BOLD) effect is most widely used. T2* weighted echo planar imaging (EPI) is BOLD sensitive and the prevailing fMRI acquisition technique. Here, we present an alternative to its standard Cartesian recordings, i.e. k-space density weighted EPI, which is expected to increase the signal-to-noise ratio in fMRI data. Based on in vitro and in vivo pilot measurements, we show that fMRI by k-space density weighted EPI is feasible and that this new acquisition technique in fact boosted spatial and temporal SNR as well as the detection of local fMRI activations. Spatial resolution, spatial response function and echo time were identical for density weighted and conventional Cartesian EPI. The signal-to-noise ratio gain of density weighting can improve activation detection and has the potential to further increase the sensitivity of fMRI investigations.
功能磁共振成像（fMRI）已成为一种强大且有影响力的方法，可用于非侵入性地研究神经元脑活动。为此，血氧水平依赖（BOLD）效应是最广泛使用的方法。T2*加权回波平面成像（EPI）对 BOLD 敏感，是流行的 fMRI 采集技术。在这里，我们提出了一种替代其标准笛卡尔记录的方法，即 K 空间密度加权 EPI，预计这将增加 fMRI 数据中的信噪比。基于体外和体内初步测量，我们证明了 K 空间密度加权 EPI 的 fMRI 是可行的，并且这种新的采集技术实际上提高了空间和时间 SNR 以及局部 fMRI 激活的检测。密度加权和常规笛卡尔 EPI 的空间分辨率、空间响应函数和回波时间相同。密度加权的信噪比增益可以提高激活检测的灵敏度，并有可能进一步提高 fMRI 研究的灵敏度。
