Understanding Loss Mechanisms in Double-Tuned Body Coils To Improve B1 Efficiency

Double-tuned circuits are often comprised of internal resonances in tank circuits that locally may amplify RF currents and thereby cause extra loss compared to single tuned RF coils. Here, we investigated the loss mechanisms of RF borecoils for the operating frequencies of 120.68, 78.8 and 45.8MHz for the purpose to design a B1+ efficient multi-tuned RF borecoil for metabolic MRI of 2H, 23Na and 31P, respectively at 7T.