Magnitude and phase signal detection in complex-valued fMRI data.

In a recent paper on complex-valued functional magnetic resonance imaging (fMRI) detection by Lee et al. (2007), a statistical model for magnitude and phase changes is presented (1). This follows a line of published research on the topic (2–5) motivated by the fact that fMRI phase data contains biological information regarding the vasculature contained within voxels (6,7). The Lee et al. (2007) model is elegant and computationally efficient, but there are four items regarding it that need to be clarified in addition to its relationship to the Rowe (2005) model (5). The Rowe (2005) model for detecting magnitude and phase changes in complex-valued data is