Complex Activation Suppresses Venous BOLD in GE-EPI FMRI Data
Rowe D, Nencka A
Medical College of Wisconsin
The phase portion of complex-valued fMRI time courses is generally discarded. There is useful temporal information in the phase regarding vascular effects that can be used to suppress activation in undesirable voxels. Nearly all fMRI studies derive functional activation based on magnitude-only data. Recently a magnitude activation from complex data with constant phase model was introduced (Rowe and Logan, 2004). Recently interest has arisen to suppress large-vessel BOLD signals postacquisition in high-resolution gradient echo EPI fMRI data by a phase regressor model (Menon, 2002) and the aforementioned complex model. However these two image analysis methods have not been examined together.