Variable Geometry Elliptical Transceiver Phased Array for Imaging of the Human Brain at 7 T

Introduction: Despite the availability of 7T systems dating from late 1990s, their use in clinical applications has been slowed by technical hurdles associated with detector design. This limitation is due to increased power deposition and B1 inhomogeneity for conventional volume coils (1). To overcome this limitation substantial effort has focused on the use of transceiver phased arrays with independent amplitude and phase control (2-5). The performance of the phased array can be further optimized by adjusting the array’s geometry to accommodate heads of various sizes. However, changes in coil coupling resulting from different loading conditions complicate its construction and use (5). We have developed an 8 element 7T transceiver split phased array with selectable geometry and a method for individualized optimization of the RF phases and amplitudes. This design allowed substantial improvement in coil’s efficiency and homogeneity.