Improved Homogeneity of the Transmit Field due to Simultaneous Transmission with Phased Arrays and Volume Coils.
Avdievich N, Hetherington H
Albert Einstein College of Medicine, Gruss MRRC
Due to RF field/ tissue interactions at high-field, 4-8T, the transmit field from head-sized volume coils shows a distinctive pattern of inhomogeneity, with enhanced sensitivity in the center of the brain. Conversely, surface coil phased arrays provide increased peripheral sensitivity. In theory, simultaneous transmission from these two devices could provide a very homogeneous transmission field. To avoid interactions between the two coils, a counter rotating current (CRC) surface coil consisting of two parallel rings carrying opposite currents was used. Using this system enables substantial improvements in the homogeneity of the transmit B1 profile as compared to the volume coil alone.