Magnetic resonance imaging (MRI) and spectroscopy (MRS) using simultaneous 2-channel acquisitions: Application for mouse brain examination by reconfiguration of a "standard" Bruker spectrometer

In the field of small animal imaging, the interest for phased array coil imaging is growing but high field MR experimental systems with multiple receiver channels are still rare and the upgrade of existing systems is relatively expensive. In this work, a standard 4.7 T Bruker Biospec Avance II spectrometer was modified to allow simultaneous two-channel acquisitions. Modifications were validated on imaging and spectroscopy on metabolite solution phantom as well as on mice brain using a home-made two-channel array coil operating at 200.3 MHz. A dedicated two-channel array coil with two square elements encompassing the mouse brain was designed and built. Compared to a singlechannel surface coil, the mean SNR measured on images in the ROI corresponding to whole mouse brain was improved by about 30% as well as the signal uniformity. For spectroscopic acquisition, the SNR gain in a voxel located close to the coils was improved by about 65%. Modifications realized for proton multiple-channel acquisitions could also be applied for any X-nucleus. Compared to quadrature detection coils, two-channel coils offer the ability to use parallel acquisitions techniques.