Dynamic Estimation of Respiration-Induced B0 Inhomogeneities in OSSI fMRI: A Novel Framework Using FIDNavs and SENSE Maps

Motivation: In OSSI fMRI, temporal fluctuations in the B0 field, predominantly resulting from respiration, can induce changes to the steady state, subsequently diminishing the temporal signal-to-noise ratio (tSNR)Goal(s): Our objective is to develop an efficient technique for estimating respiration-induced B0 variations in OSSI fMRIApproach: We have used Free Induction Decay (FID) frequency offset to estimate the first-order field inhomogeneities. A novel element in our approach lies in adopting a spatial encoding strategy for these FIDs, drawing on the geometric centroids of each coil's sensitivity profileResults: Our initial findings indicates comparable results between our FIDNavs method and image-based field map method. Impact: This approach allows for a rapid measurement of B0 variations, thus facilitating faster real-time corrections. This method bypasses the lengthy process of calibration or the need for reference images.