Improved activation detection from magnitude and phase functional MRI data

Oregon Convention Center 

Functional MRI is a popular noninvasive technique for mapping brain regions activated by specific brain functions. However, as fMRI measures brain activity indirectly through blood flow, the so-called "brain or vein" problem refers to the difficulty in determining whether measured activation corresponds to (desired) brain tissue or (undesired) large veins, which may be draining blood from neighboring regions. Now, fMRI data consist of both magnitude and phase components (i.e., it is complex-valued), but in the vast majority of statistical analyses, only the magnitude data is utilized. However, while activation in the magnitude component can come from both "brain or vein", previous work has demonstrated that activation in the phase component "discriminates" between the two: phase activation occurs in voxels with large, oriented vessels but not in voxels with small, randomly oriented vessels immediately adjacent to brain tissue. Following this motivation, we have developed a model that allows for activation in magnitude and phase, one more general than those previously proposed.

functional MRI

Imaging 

Section on Statistics in Imaging