A Dedicated Two-Channel Phased-Array Receiver Coil for High-Resolution MRI of the Rat Knee Cartilage at 7 T

In the field of small animal studies, the array coil imaging has become increasingly important. In this paper, a dedicated two-channel array coil operating at 300 MHz (7 T) for high-resolution MRI (HR-MRI) of the rat knee cartilage is presented. The average gain in signal-to-noise ratio (SNR) compared to a 15-mm multipurpose surface coil was 2.2. This SNR gain was used to improve the spatial resolution of 3-D acquisitions by decreasing the voxel size from 59$,times,$59 $,times,$156 $mu$m $^3$ to 51$,times,$51 $,times,$94 $mu$ m$^3$ without time penalty. Also, a set of two array coils was used to perform a simultaneous acquisition of both knee joints of a rat, maintaining the same scanning time without SNR or spatial resolution degradation compared to the single knee joint acquisition. This two-channel array coil is a key element to perform HR-MRI and extract cartilage morphological parameters such as thickness and volume.