Enabling brain-wide mapping of directed functional connectivity at 3T via layer-dependent fMRI with draining-vein suppression.
Enabling brain-wide mapping of directed functional connectivity at 3T via layer-dependent fMRI with draining-vein suppression.
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通过层依赖性 fMRI 和引流静脉抑制，实现 3T 定向功能连接的全脑映射。
DOI：
10.1101/2023.10.24.563835
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Giovanello,KellyS
中科院分区：
文献类型：
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作者：
Chang,Wei-Tang;Lin,Weili;Giovanello,KellyS
层依赖性功能磁共振成像（fMRI）是一种研究层特异性功能连接（FC）的有前途但具有挑战性的方法。实现层特异性FC的全脑映射需要几项技术进步，包括亚毫米空间分辨率、足够的时间分辨率、功能灵敏度、全脑覆盖和高空间特异性。尽管基于梯度回波（GE）的回波平面成像（EPI）通常用于快速fMRI采集，但由于引流静脉污染，它面临着重大挑战。在这项研究中，我们解决了这些局限性，将速度归零（VN）梯度到GE-BOLD功能磁共振成像序列，以抑制血管信号的血管与快速流动的速度。使用3 T而不是7 T的GE-EPI序列，结合相位回归方法，减轻了软脑膜静脉的血管外污染。此外，我们还采用了先进的技术，包括同步多切片（SMS）加速和噪声降低与扩散校正主成分分析（NORDIC PCA）去噪，以提高时间分辨率，空间覆盖范围和信号灵敏度。这导致VN fMRI序列具有0.9 mm各向同性空间分辨率，4秒的重复时间（TR）和全脑覆盖。VN梯度强度是根据按钮按压任务的结果确定的。使用静息状态数据，我们通过基于种子的分析验证了层特异性FC，识别了初级运动皮层（M1）浅层和深层的不同连接模式，具有显着的层间差异。对初级感觉皮层（S1）中种子的进一步分析证明了该方法的可靠性。全脑层依赖的FC分析产生的结果与以前的文献一致，加强了VN功能磁共振成像在解决特定层的功能连接的功效。鉴于3 T扫描仪的广泛应用，这一技术进步有可能对神经科学研究的多个领域产生重大影响。
Layer-dependent functional magnetic resonance imaging (fMRI) is a promising yet challenging approach for investigating layer-specific functional connectivity (FC). Achieving a brain-wide mapping of layer-specific FC requires several technical advancements, including sub-millimeter spatial resolution, sufficient temporal resolution, functional sensitivity, global brain coverage, and high spatial specificity. Although gradient echo (GE)–based echo planar imaging (EPI) is commonly used for rapid fMRI acquisition, it faces significant challenges due to the draining-vein contamination. In this study, we addressed these limitations by integrating velocity-nulling (VN) gradients into a GE-BOLD fMRI sequence to suppress vascular signals from the vessels with fast-flowing velocity. The extravascular contamination from pial veins was mitigated using a GE-EPI sequence at 3T rather than 7T, combined with phase regression methods. Additionally, we incorporated advanced techniques, including simultaneous multi-slice (SMS) acceleration and NOise Reduction with DIstribution Corrected principal component analysis (NORDIC PCA) denoising, to improve temporal resolution, spatial coverage, and signal sensitivity. This resulted in a VN fMRI sequence with 0.9-mm isotropic spatial resolution, a repetition time (TR) of 4 seconds, and brain-wide coverage. The VN gradient strength was determined based on results from a button-pressing task. Using resting-state data, we validated layer-specific FC through seed-based analyses, identifying distinct connectivity patterns in the superficial and deep layers of the primary motor cortex (M1), with significant inter-layer differences. Further analyses with a seed in the primary sensory cortex (S1) demonstrated the reliability of the method. Brain-wide layer-dependent FC analyses yielded results consistent with prior literature, reinforcing the efficacy of VN fMRI in resolving layer-specific functional connectivity. Given the widespread availability of 3T scanners, this technical advancement has the potential for significant impact across multiple domains of neuroscience research.