Abstract #4501

Optimal Flip Angle Range for B1+ Mapping at 3T with Slice Profile Correction Using a Dual Angle EPI Sequence

Gabriela Belsley¹, Damian J. Tyler¹, Matthew D. Robson^1,2, and Elizabeth M. Tunnicliffe ¹

¹Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom, ²Perspectum Diagnostics, Oxford, United Kingdom

Mapping B₁+ inhomogeneity, using commonly available pulse sequences, is essential for widespread, accurate determination of T₁ using variable flip angle methods. We investigated the accuracy of B₁+ mapping with different flip angles (FA) using the double angle method with a 2D multi-slice GRE-EPI sequence. At lower FAs, we found that B₁+ accuracy is affected by SNR, whereas the extent of B₁+ inhomogeneities imposes an upper limit on the FAs that can be employed. For a B₁+ inhomogeneity of ±40% and a SNR of 29 at 30°, the optimal FA pairs were found to lie between 43°/86° and 74°/148°.

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