  It is technically challenging to design efficient transceiver coil arrays for
foot and ankle imaging at ultrahigh fields due to the irregular geometry of the
anatomy. Shortened wavelength because of the high operation frequency at
ultrahigh fields increases phase variation, leading to inhomogeneous B1
distribution in the imaging sample. In this work, we propose a hybrid design
with mixed L-C loops and microstrip resonators for multichannel foot/ankle
transceiver arrays at the ultrahigh field of 7T. The proposed transceiver array
consists of 14 microstrip resonators and 5 L-C loop coils to cover the entire
region of interest of the irregular-shaped foot/ankle with a relatively uniform
B1 distribution at 7T. The feasibility and field behavior of the proposed
design are systematically investigated numerically.
