Fast and Motion Robust R2* Reconstruction for Functional MRI

Valur Olafsson¹, Jeffrey A. Fessler¹, Douglas C. Noll²

Quantitative images such as R2* maps are beneficial in understanding the BOLD contrast commonly used for functional MRI. However, due to its non-linear relationship to the MR signal equation it is problematic to efficiently estimate it directly from k-space data. We propose a new fast reconstruction that uses a linear approximation facilitated by a reference image to reconstruct R2* along with field map and M0 to make it robust to motion. Results from an fMRI experiment shows increased functional sensitivity for the R2* images compared to conventional T2*-weighted images and a reconstruction time just under a minute per slice.