A 7T 8 channel transmit-receive dipole array for head imaging: dipole element and coil evaluation

Target audience: Radiofrequency (RF) engineers, anyone interested in high field RF coils, parallel transmit or high field brain imaging. Introduction: Electric dipole antennas are seeing increasing use for 7T MR imaging. They differ from conventional surface coil loops in many ways. With 8 elements surrounding a body sized tissue equivalent phantom and array of dipole antennas can achieve higher central SNR than an array of loops, while simultaneously having greater coverage along Z. Most 7T head coils today rely on birdcage or TEM volume coils for transmit, or arrays of loops. Signal dropout in inferior brain regions such as the cerebellum and brain stem is a common problem. We describe here a dipole array for 7T head imaging designed for extended coverage and evaluate its performance in phantom and volunteer imaging.