An improved asymmetric gradient coil design for high-resolution MRI head imaging.

For head magnetic resonance imaging, local gradient coils are often used to achieve high solution images. To accommodate the human head and shoulder, the head gradient coils are usually designed in an asymmetric configuration, allowing the region-of-uniformity (ROU) close to the coil's patient end. However, the asymmetric configuration leads to technical difficulties in maintaining a high gradient performance for the insertable head coil with very limited space. In this work, we present a practical design configuration of an asymmetric insertable gradient head coil offering an improved performance. In the proposed design, at the patient end, the primary and secondary coils are connected using an additional radial surface, thus allowing the coil conductors distributed on the flange to ensure an improvement in the coil performance. At the service end, the primary and shielding coils are not connected, to permit access to shim trays, cooling system piping, cabling, and so on. The new designs are compared with conventional coil configurations and the simulation results show that, with a similar field quality in the ROU, the proposed coil pattern has improved construction characteristics (open service end, well-distributed wire pattern) and offers a better coil performance (lower inductance, higher efficiency, etc) than conventional head coil configurations.