Goodyear Bradley G, Douglas Erin A
Department of Radiology, University of Calgary, Calgary, AB Canada.
J Magn Reson Imaging. 2008 Nov;28(5):1055-60. doi: 10.1002/jmri.21347.
To determine the minimum detectable change (MDC) in functional magnetic resonance imaging (fMRI) measurements of brain activity over repeated sessions with 95% confidence using a block design of tasks.
Fourteen individuals participated in three sessions on different days during which four scans each of a motor task and working memory task were performed. Using a region-of-interest analysis of variance, we calculated the MDC in the volume of activated primary sensorimotor cortex (for motor) and dorsolateral prefrontal cortex (for working memory), as well as the percent increase in MR signal and the center and location of maxima of the activated voxels.
The MDC of activated volume was 5.0-8.8 cm3, and the MDC of percent increase in signal from baseline during tasks was 0.3%-0.6%. The MDC of the center of mass of activity was 3-4 mm, compared to 6-10 mm for the location of maxima.
fMRI measurements that quantify the strength of activity in response to tasks and centers of mass offer sensitive measurements of change over repeated imaging sessions. fMRI can be used for serial investigations of individual participants using simple motor and cognitive tasks using a simple block design.
使用任务组块设计，确定在重复实验环节中脑功能磁共振成像（fMRI）对脑活动测量的最小可检测变化（MDC），置信度为95%。
14名受试者在不同日期参加了三个实验环节，每个环节中对运动任务和工作记忆任务各进行4次扫描。通过感兴趣区方差分析，我们计算了激活的初级感觉运动皮层（运动任务）和背外侧前额叶皮层（工作记忆任务）体积的MDC，以及磁共振信号的百分比增加量、激活体素最大值的中心和位置。
激活体积的MDC为5.0 - 8.8立方厘米，任务期间相对于基线信号百分比增加量的MDC为0.3% - 0.6%。活动质心的MDC为3 - 4毫米，而最大值位置的MDC为6 - 10毫米。
fMRI测量可量化任务响应活动强度和质心，能为重复成像实验环节中的变化提供灵敏测量。fMRI可用于对个体受试者进行连续研究，采用简单的组块设计，运用简单的运动和认知任务。
