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Abstract

Conductivity emerges as a valuable tool for both diagnostic and therapeutic applications. Utilizing complex B1 fields in MRI, conductivity calculations can be achieved non-invasively and without the need for additional hardware. However, existing methods face challenges in translating this capability into clinical settings due to slow acquisition times, with initial experiments taking over half an hour and even exceeding 8 hours with multi-transmit schemes. This work addresses these limitations by introducing new acquisition schemes for both B1 magnitude and phase. Specifically, for B1 magnitude, an undersampling approach coupled with Total Generalized Variation regularization was implemented, demonstrating an impressive 85-fold acceleration in phantom experiments without compromising image quality. For B1 phase, variable density spiral acquisitions were employed and combined with the SPIRiT parallel imaging technique for image quality enhancement. Phantom and in vivo experiments illustrated close agreement between calculated and expected conductivity values. This acquisition scheme enables the acquisition of a single slice with multiple averages within a second, while achieving whole brain coverage in just a minute. In conclusion, this work substantially reduces overall acquisition time, making it possible to map B1 magnitude and phase for the whole-brain in less than 2 minutes, thereby enhancing the practicality of MRI-based conductivity imaging in clinical applications.