Systematic Artifact Reduction in Auditory fMRI

描述（由申请人提供）：使用回波平面成像（EPI）的功能性磁共振成像（fMRI）导致产生系统性混杂声学噪声（“声学成像噪声”），其可干扰与所需（声学）刺激相关的皮质活动的fMRI测量。声学成像噪声可被听力受试者感知，导致整个听觉通路（包括皮层）的神经元活动。声成像噪声的感知可以改变对所需刺激的感官感知，这种改变将影响生理活动并扭曲对所需刺激的血液动力学反应（HDR）的测量。方法，最初针对听觉功能磁共振成像，提出了开发校正算法，可用于校正与系统混淆相关的“理想”HDR（在没有混淆的情况下测量）的失真。校正算法的开发过程对功能磁共振成像领域产生了重大的益处，因为该过程可以应用于已知与功能磁共振成像数据采集相关的其他系统性混淆。本研究的具体目标概括如下：目标1：获得“理想”的测量HDR的系统混淆的声成像噪声的blipped-EPI在1.5T。目标二：获得HDR对所需（声学）刺激的非理想测量，通过系统混杂（声学成像噪声）的变化进行参数化，从而允许量化HDR之间的相互作用。目标3：开发校正算法，以补偿所需（声学）刺激的非理想HDR测量中存在的失真，使得所得HDR估计类似于在不存在系统混淆（声学成像噪声）的情况下获得的估计。相关性：在存在重复混淆（例如，与成像相关的声学噪声）将允许更精确地区分对刺激的皮层响应，所述刺激可能仅以细微的方式不同。这些益处将为检测到的活动的位置和程度提供更大的置信度，显著影响人脑映射，但也直接有益于术前映射的努力。

DESCRIPTION (provided by applicant): 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.