Cryogenically cooled MRI coils demonstrate extremely high Q-factors leading to a very narrow bandwidth. This bandwidth can be increased in a controlled manner using a preamplifier decoupling. In this work, an MRI coil design procedure is explained and an example showing over 2 times bandwidth increase in a cryogenic coil for 13C isotope imaging in 3-tesla MRI systems is demonstrated. The achieved wider bandwidth preserves the spectral components of magnetic resonance signals and makes coils less susceptive to detuning due to parasitic coupling to surrounding structures. The presented method is also useful in other applications of high-Q coils, for instance, in low field magnetic resonance imaging systems.

The perspective of extending bandwidth of an MRI detector to ~3.2MHz can enable imaging of 13C, 23Na and 129Xe nuclei with a single coil in 3T scanners. Currently, multinuclear imaging is done using bulky multi-coil setups or triple-tuned matching networks. In this work we propose a different approach to cover several nuclei frequencies by extending the bandwidth of a single receive coil manipulating impedance of the preamplifiers. A trade-off analysis of the achieved bandwidth and SNR is performed. A design example is presented. The approach promises compact and light-weight realization, which is particularly useful for ultra-flexible multinuclear receive arrays.

Self-resonant coils are well suitable for flexible array design. The size of such coils is dictated by the RF signal wavelength, which makes the design challenging at low frequencies. In this work, 13C tuning is achieved by combining distributed and lumped capacitance with the self-inductance of an RG-178 coaxial cable. A 1H trap is moved from the coil to the board of the preamplifier for better coil flexibility. The active 13C decoupling circuit is compact and broadband. The approach is used to develop a flexible 8-channel receive array of parallel-resonance coils for 13C-imaging. The array elements exhibit low noise correlation.