Reducing SAR and Imaging Time at 7T Using RF Multiplexing and Transceiver Arrays at 7T

Hoby P. Hetherington¹, Nikolai I. Avdievich¹, Jullie Pan¹

At 7T, decreasing T2, T2* and increasing SAR and T1 can limit the number of slices acquired or acquisition time. RF multiplexing enables coil dense transceiver arrays (more coils than independent RF channels) to be used; which improves SNR (more optimal coil size and number) and B1 homogeneity and coverage. RF multiplexing inherently generates simultaneous multiple bands of excitation for slice selective pulses. The aliasing generated by the multiple bands of excitation can be removed by deconvolution with the receiver sensitivity matrix to regenerate three independent slices, thereby reducing SAR and increasing imaging speed by acquiring three slices per excitation.