Design of quadrature switchable coils for optimum anatomic coverage and signal-to-noise ratio

The purpose of this study is to determine the optimum geometry for a whole-spine switchable-array coil that uses the asymmetric quadrature principle, with overlapped coil elements enabled separately for high-resolution imaging of a small field of view (FOC) or simultaneously for imaging of a large FOV. A quadrature design must minimize mutual coupling between adjacent coils in the array and also maintain orthogonality in an individual element to prevent low-intensity signal regions between coils and to prevent signal-to-noise ratio(S/N) degradation due to imperfect signal combination. The authors present a design in which coil interaction is kept below 20 dB and quadrature isolation is better than 24 dB; the system produces images with significantly higher S/N and coverage than earlier linear arrays