Systematic Artifact Reduction in Auditory fMRI

使用回波平面成像(EPI)的功能磁共振成像(FMRI)导致产生 干扰脑功能磁共振测量的系统性混杂声学噪声(“声学成像噪声”) 与期望的(声学)刺激相关的皮质活动。声学成像噪声不可避免地被一种 听力受试者，导致神经元活动贯穿整个听觉通路，包括皮质。对 声成像噪声可以改变对所需刺激的感官感知--这一改变将影响生理 对所需刺激的血流动力学反应(HDR)的活动性和失真测量。方法，最初 针对听觉fMRI，提出了开发可用于校正失真的校正算法 与系统性混淆相关的“理想”HDR(在没有混淆的情况下测量的)。意义重大 对fMRI社区的好处来自于开发校正算法的过程，因为 该方法可应用于已知与fMRI数据采集相关的其他系统性混淆。 本研究的具体目的概括如下： 目标1：获得系统混淆的声成像噪声的HDR的“理想”测量 闪光灯-1.5T的EPI。 目标2：获得对所需(声)刺激的HDR的非理想测量，通过以下变化进行参数化 系统混淆(声成像噪声)，使HDR之间的相互作用得以量化。 目标3：开发校正算法，以补偿非理想HDR测量中存在的失真 期望的(声学)刺激，使得所得到的HDR估计类似于在没有HDR的情况下将获得的估计 系统性混淆(声像噪声)。 相关性：改进了FMRI实验的定位准确性和检测灵敏度 重复混杂的存在(例如，与成像相关的声学噪声)将允许更精确 大脑皮质对刺激反应的辨别能力，可能只是以一种微妙的方式有所不同。这些好处将提供 对检测到的活动的位置和程度的更大信心，显著影响人类脑图，但也 直接受益于手术前测绘的努力。

Functional magnetic resonance imaging (fMRI) using echo-planar imaging (EPI) results in generation of a systematic confound¿acoustic noise ("acoustic imaging noise")¿that can interfere with the fMRI measurement of cortical activity related to a desired (acoustic) stimulus. Acoustic imaging noise is unavoidably perceived by a hearing subject, leading to neuronal activity throughout the auditory pathway, including cortex. Perception of acoustic imaging noise can alter sensory perception of the desired stimulus¿an alteration that will affect physiologic activity and distort measurement of the hemodynamic response (HDR) to the desired stimulus. Methods, initially directed at auditory fMRI, are proposed to develop correction algorithms that may be used to correct distortions of the "ideal" HDR (that measured in the absence of confound) associated with systematic confounds. Significant benefit to the fMRI community arises from the process by which the correction algorithm is developed, as the process may be applied to other systematic confounds known to be associated with acquisition of fMRI data. The specific aims of this research are summarized as follows: Aim 1: Obtain "ideal" measurements of the HDR to the systematic confound of acoustic imaging noise for blipped-EPI at 1.5T. Aim 2: Obtain non-ideal measurements of HDRs to a desired (acoustic) stimulus, parameterized by variations in the systematic confound (acoustic imaging noise), allowing quantification of interactions between the HDRs. Aim 3: Develop correction algorithms to compensate for distortions present in non-ideal HDR measurements to a desired (acoustic) stimulus, such that resulting HDR estimates resemble those which would be obtained in absence of the systematic confound (acoustic imaging noise). Relevance: Improvements in localization accuracy and detection sensitivity for fMRI experiments conducted in the presence of repeated confounds (e.g., acoustic noise associated with imaging) will allow more precise discrimination of cortical responses to stimuli that may differ only in a subtle fashion. These benefits will provide greater confidence in location and extent of detected activity, significantly impacting human brain mapping, but also directly benefiting efforts at pre-surgical mapping.