Improved signal linearity for channel-wise relative B1+ mapping at 7T with an interleaved acquisition scheme

Motivation: A common relative B1+ mapping approach relies on channel-wise acquisitions in the small flip angle regime. However, staying within this linear regime is not trivial for certain applications. Goal(s): We evaluated whether an interleaved acquisition scheme enables a more robust measurement of relative B1+ maps, compared to the conventional sequential scheme. Approach: For both acquisition schemes, validation phantom measurements were acquired and simulations were performed for phantom, heart and prostate data. The signal linearity was evaluated. Results: Validation measurements matched well with the simulation results. The interleaved acquisition scheme resulted in smaller errors compared to the sequential scheme in all simulated cases. Impact: Compared to the conventional sequential scheme, an interleaved acquisition of channel-wise relative B1+ maps mitigates the risk of errors from exceeding the linear regime, enhancing accuracy for applications susceptible to this issue, such as body imaging at 7T.