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Abstract #4431

RF Pulse Optimization for Bloch-Siegert B1+ Mapping

Mohammad Mehdi Khalighi1, Brian K. Rutt2, Manojkumar Saranathan2, Adam B. Kerr3

1Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States; 2Department of Radiology, Stanford University, Stanford, CA, United States; 3Department of Electrical Engineering, Stanford University, Stanford, CA, United States

B1+ mapping by the Bloch-Siegert (BS) method has been shown to be fast and accurate; however, at high field it suffers from high SAR and long TE, which results in lengthened scan times and signal loss due to B0 inhomogeneity. We have designed a new BS RF pulse that can be applied closer to the water resonance yet still limits excitation within the on-resonant band of interest. Comparison of BS B1+ mapping using the new pulse versus the conventional Fermi pulse in both phantoms and human brain shows improved B1+ map quality with substantial reductions in both TE and SAR.