A transmit–receive array for brain imaging with a high‐performance gradient insert

Purpose The aim of this work was to provide parallel imaging capability for the human head in a gradient insert of 33‐cm inner diameter within the related constraints of space, encoding ambiguity, and eddy current immunity. Methods Eddy current behavior of the 8‐channel transmit–receive array coil was investigated via heating and field deviation measurements. RF performance was evaluated using S‐parameters, noise statistics, B1 maps, and g‐factor maps. In vivo images of a human head and knee were acquired with Cartesian readout and TE below 0.45 ms. Results Under intense gradient use, the shield was heated up to 55°C and other coil structures to 40°C. After standard preemphasis calibration, eddy current‐related field distortions caused by the developed RF coil were smaller than for a commercial receive‐only coil. In the ambiguous regions of the gradient, B1+ is 20 dB lower than in the center of the FOV. Coupling between elements is below −15 dB, and noise correlation is less than 0.31 when the coil is loaded with a head. Power efficiency was 0.52 ± 0.02 μT/√W, and the SD of the flip angle was below 10% in central slices of the brain. 2D, up to fourfold acceleration causes less than 30% noise amplification. The RF coil can be used during full gradient performance. Conclusion Based on the described features, the presented coil enables parallel imaging in the high‐performance gradient insert.