A deconvolution algorithm for multi-echo functional MRI: Multi-echo Sparse Paradigm Free Mapping
A deconvolution algorithm for multi-echo functional MRI: Multi-echo Sparse Paradigm Free Mapping
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DOI：
10.1016/j.neuroimage.2019.116081
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发表时间：
2019-11-15
期刊：
影响因子：
5.7
通讯作者：
Gonzalez-Castillo, Javier
中科院分区：
文献类型：
--
作者：
Caballero-Gaudes, Cesar;Moia, Stefano;Gonzalez-Castillo, Javier
这项工作介绍了一种用于多回波 fMRI 数据中 BOLD 信号去卷积的新颖算法：多回波稀疏范式自由映射 (ME-SPFM)。假设 BOLD 百分比信号变化与回波时间 (TE) 呈线性相关，并使用稀疏性促进正则化最小二乘估计，ME-SPFM 可以生成表观横向弛豫 (Delta R-2*) 变化的体素时变估计，而无需事先了解各个 BOLD 事件的时间。我们在 3 特斯拉多任务事件相关范例期间收集的多回波 fMRI 数据结果表明，在刺激试验时使用 ME-SPFM 获得的 R-2* 变化图与通过基于标准模型的分析获得的激活图和 BOLD 信号显示出高度的空间和时间一致性。该方法产生具有生理合理值的 Delta R-2* 估计值。由于具有盲目检测事件的能力，ME-SPFM 还使我们能够绘制与试验之间发生的自发、短暂 BOLD 反应相关的 Delta R-2*。该框架是朝着破译自然主义范式、静息态或实验范式中大胆事件时间未知的大脑活动的动态本质迈出的一步。
This work introduces a novel algorithm for deconvolution of the BOLD signal in multi-echo fMRI data: Multi-echo Sparse Paradigm Free Mapping (ME-SPFM). Assuming a linear dependence of the BOLD percent signal change on the echo time (TE) and using sparsity-promoting regularized least squares estimation, ME-SPFM yields voxelwise time-varying estimates of the changes in the apparent transverse relaxation (Delta R-2*) without prior knowledge of the timings of individual BOLD events. Our results in multi-echo fMRI data collected during a multi-task event-related paradigm at 3 Tesla demonstrate that the maps of R-2* changes obtained with ME-SPFM at the times of the stimulus trials show high spatial and temporal concordance with the activation maps and BOLD signals obtained with standard model-based analysis. This method yields estimates of Delta R-2* having physiologically plausible values. Owing to its ability to blindly detect events, ME-SPFM also enables us to map Delta R-2* associated with spontaneous, transient BOLD responses occurring between trials. This framework is a step towards deciphering the dynamic nature of brain activity in naturalistic paradigms, resting-state or experimental paradigms with unknown timing of the BOLD events.