Cardiac-incoherent sampling of transverse signal decay mitigates cardiac-induced noise in brain maps of R2*

Motivation: Robust measures of the relaxation rate R2* are essential for use in neuroscience studies. With standard acquisition techniques, data are sampled consecutively at multiple echo times at the same phase of the cardiac cycle. This coherent sampling leads to a high level of cardiac-induced noise in brain maps of R2*. Goal(s): We design a new data acquisition strategy that mitigates the impact of cardiac-induced noise in brain quantitative R2* maps. Approach: We incoherently sample cardiac-induced noise by shifting k-space location during the multi-echo acquisition. Results: Compared to standard techniques, this strategy reduces the variability of R2* estimates across repetitions by 30-40%. Impact: The proposed k-space shifting acquisition strategy reduces the level of cardiac-induced noise in brain maps of R2*. This will increase the sensitivity of brain change analyses in future neuroscience studies that include R2* mapping.