Motivation: More efficient mapping of magnetic field inhomogeneities (B0 and B1+) is essential in ultra-high field MRI for individually optimizing parallel transmission pulses. Goal (s): To rapidly, simultaneously, and accurately estimate B0 and B1+ inhomogeneities at 7T. Approach: We propose a modification of the 3D B1+ mapping Sandwich sequence (CLUB-Sandwich), which integrates three monopolar echoes for ΔB0 mapping in the pre-saturation train. The CLUB-Sandwich approach is validated by comparing the estimated ΔB0 and B1+ maps to standard reference methods in five subjects. Results: Minimal differences (mean bias of 0. 9\, ±\, 4. 5 Hz and 3. 2\, ±\, 1. 1°) demonstrate reliable, fast mapping of ultra-high field inhomogeneities. Impact: The proposed CLUB-Sandwich sequence enables rapid, simultaneous ΔB0 and B1+ mapping at 7T without accuracy reduction, providing a faster method for optimizing parallel transmission pulses, increasing efficiency in ultra-high field MRI applications.
Montemayor et al. (Tue,) studied this question.