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Abstract #0578

Single-Shot Spiral Based Bloch-Siegert B1+ Mapping

Mohammad Mehdi Khalighi1, Gary H. Glover2, Prachi Pandit2, Scott Hinks3, Adam B. Kerr4, Manojkumar Saranathan2, Brian K. Rutt2

1Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, USA; 2Department of Radiology, Stanford University, Stanford, CA, USA; 3Global Applied Science Laboratory, GE Healthcare, Waukesha, WI, USA; 4Department of Electrical Engineering, Stanford University, Stanford, CA, USA

Fast and accurate B1+ mapping is needed in high field MRI for different applications like parallel transmit or quantitative relaxometry. Bloch-Siegert (BS) B1+ mapping is an accurate method; however it suffers from high RF deposition (SAR) at high field and consequently long scan times. To overcome this limitation, we have integrated the BS method into a single-shot spiral sequence at 7T, and have shown that it reduces SAR and scantime significantly, with similar angle-to-noise ratio, compared to a gradient echo based BS method. Whole-brain B1+ maps can be obtained at 7T in less than 10 seconds using the new method.