A comparison of dynamic and static B0 mapping approaches for correction of CEST MRI at 7T.

In contrast to established static B0 correction approaches which assume an invariant static field during a CEST MRI acquisition, we propose three methods which can track and compensate temporal B0 fluctuations by shifting each Z-spectral point separately before MTRasym analysis. We show the benefit of the proposed dynamic methods in comparison to three established static approaches by assessing their performance in the absence/presence of an induced frequency drift. In addition, we investigate the reliability and reproducibility of CEST MRI at ultra-high field (7T) by evaluating the drift’s impact on the B0-corrected MTRasym maps in the brains of five healthy volunteers.