Evaluating fMRI Spatial Extent in Groups with Different CNR

Equation 1 where x, x, and nx are the sample mean, sample standard deviation, and number of samples from condition x. [2] A common objective of functional magnetic resonance imaging (fMRI) is to evaluate of the spatial extent of brain activation in one or more groups. These groups may consist of longitudinal studies within the same subject or comparison across differing subject populations. A common approach to evaluating spatial extent is to count the number of voxels that meet a specified statistical criteria. However, if the different groups do not have the same contrast-to-noise (CNR), the spatial extent difference will be related to both the CNR differences and the functional differences between the groups [1]. In order to fairly compare the spatial extent of activations with different CNR, one must account for the CNR differences between the statistical maps. The goal of this research was to develop a method to allow comparison of the spatial extent of activations between two different groups for statistical maps calculated using a t-statistic. Evaluating fMRI Spatial Extent in Groups with Different CNR