Kundu Prantik, Benson Brenda E, Baldwin Katherine L, Rosen Dana, Luh Wen-Ming, Bandettini Peter A, Pine Daniel S, Ernst Monique
Section on Functional Imaging Methods, National Institute of Mental Health, Bethesda, MD, 20892, USA,
Brain Imaging Behav. 2015 Mar;9(1):56-73. doi: 10.1007/s11682-014-9346-4.
Several methodological challenges affect the study of typical brain development based on resting state blood oxygenation level dependent (BOLD) functional MRI (fMRI). One such challenge is mitigating artifacts such as those from head motion, known to be more substantial in younger subjects than older subjects. Other challenges include controlling for potential age-dependence in cerebrospinal fluid (CSF) volume affecting anatomical-functional coregistration; in vascular density affecting BOLD contrast-to-noise; and in CSF pulsation creating time series artifacts. Historically, these confounds have been approached through incorporating artifact-specific temporal and/or spatial filtering into preprocessing pipelines. However, such paths often come with new confounds or limitations. In this study we take the approach of a bottom-up revision of fMRI methodology based on acquisition of multi-echo fMRI and comprehensive utilization of the information in the TE-domain to enhance several aspects of fMRI analysis in the context of a developmental study. We show in a cohort of 25 healthy subjects, aged 9 to 43 years, that the analysis of multi-echo fMRI data eliminates a number of arbitrary processing steps such as bandpass filtering and spatial smoothing, while enabling procedures such as [Formula: see text] mapping, BOLD contrast normalization and signal dropout recovery, precise anatomical-functional coregistration based on [Formula: see text] measurements, automatic denoising through removing subject motion, scanner-related signal drifts and physiology, as well as statistical inference for seed-based connectivity. These enhancements are of both theoretical significance and practical benefit in the study of typical brain development.
基于静息态血氧水平依赖（BOLD）功能磁共振成像（fMRI）对典型脑发育进行研究时，面临着若干方法学挑战。其中一个挑战是减轻诸如头部运动产生的伪影，已知这类伪影在年轻受试者中比在年长受试者中更显著。其他挑战包括控制脑脊液（CSF）体积中可能存在的年龄依赖性，其会影响解剖 - 功能配准；血管密度的年龄依赖性会影响BOLD对比噪声；以及脑脊液搏动会产生时间序列伪影。从历史上看，这些混杂因素是通过在预处理流程中纳入特定于伪影的时间和/或空间滤波来解决的。然而，这些方法往往会带来新的混杂因素或局限性。在本研究中，我们采取自下而上修订fMRI方法的途径，该途径基于多回波fMRI的采集以及对回波时间（TE）域信息的全面利用，以在发育研究的背景下增强fMRI分析的多个方面。我们在一个由25名年龄在9至43岁之间的健康受试者组成的队列中表明，多回波fMRI数据分析消除了许多诸如带通滤波和空间平滑等任意处理步骤，同时实现了诸如[公式：见正文]映射、BOLD对比归一化和信号丢失恢复、基于[公式：见正文]测量的精确解剖 - 功能配准、通过去除受试者运动、扫描仪相关信号漂移和生理信号进行自动去噪，以及基于种子点的连通性的统计推断。这些改进在典型脑发育研究中具有理论意义和实际益处。
