Quadrature RF coil for in Vivo brain MRI of a macaque monkey in a stereotaxic head frame

Abstract

We present a quadrature volume coil designed for brain imaging of a macaque monkey fixed in a sphinx position (facing down the bore) within a stereotactic frame at 3 T, where the position of the monkey and presence of the frame preclude use of existing coils. Requirements include the ability to position and remove the coil without disturbing the position of the monkey in the frame. A saddle coil and a solenoid were combined on a modified cylindrical former and connected in quadrature as to produce a homogeneous circularly polarized field throughout the brain. To allow the loops of the saddle coil to encompass the ear posts, partial disassembly and reassembly were facilitated by embedding pin and socket contacts into separate pieces of the former. Coil design included simulation of the electromagnetic fields for the coil containing a 3D model of a monkey’s head. The resulting coil produced adequate homogeneity and signal-to-noise ratio throughout the brain.

A 16-channel loop array for in vivo macaque whole-brain imaging at 3 T

“…This can be overcome by careful coil array designs that allows for positioning and animal's head in a manner compatible with presentation of visual stimuli. Recently, a number of radiofrequency (RF) coil arrays have been designed for NHP imaging [14][15][16][17][18][19][20][21][22][23], for example, an 8-channel receive-only array coil implanted on the skull of a macaque was constructed to achieve 5.4 fold increasing in SNR when compared with a single-channel coil placed externally around the animal's head [17]; however, few have been compatible with multimodal imaging/stimulation approaches.…”