Simultaneous registration and activation detection: Overcoming activation-induced registration errors in functional MRI

In the processing of functional magnetic resonance imaging (fMRI) data, motion correction is typically performed before activation detection. However, on high-field MR scanners (3 T and higher), the strength of the blood oxygen level dependent (BOLD) signal can cause registration algorithms to produce motion estimates that have stimulus-correlated errors. Motion compensation using these biased motion estimates can result in both false-positive and false-negative regions of activation.; By formulating the registration and activation detection problems into a single least-squares problem, both the motion estimates and activation map can be solved for simultaneously. However, the solution is not unique and an additional constraint is used to find a solution that is appropriate. This constrained optimization problem can be solved efficiently, and two equivalent methods are proposed and demonstrated on both simulated and in vivo datasets.