EPI images suffer from signal dropouts and z-shimming is an effective technique to recover parts of the lost signal. Its inherent drawbacks are a scan time prolongation and the necessity to estimate subject-specific z-shim gradient moments. We introduce multi-band imaging to z-shimming to eliminate the scan time prolongation and propose a novel method to estimate optimal z-shim gradient moments. The results show less signal dropout in the z-shimmed images and prove our z-shim gradient moment estimation to be robust and efficient. Due to a reduced anatomical contrast, our multi-band z-shim approach might be most beneficial for BOLD-contrast based fMRI.
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