Resonance Shift Decoupling: A Potential Alternative to Low Input Impedance Preamplifiers

Introduction The use of phased-array coils has become desirable for efficient magnetic resonance imaging in both clinical and preclinical biological investigations. Multi-channel receivers are now commonplace, allowing the use of phased-array coils with many elements. Coupling becomes increasingly problematic with more elements, degrading the independence of coil sensitivities required for parallel imaging [1]. This ultimately results in reduced image SNR. Geometric overlap-decoupling can be used for adjacent elements; however non-adjacent elements require loop current minimization. Low input impedance (Zin) preamplifiers have traditionally been used for this purpose [2]. In this work, we tested an alternate method involving a transistor amplifier that is built into the coil to minimize loop current and maximize gain, while simultaneously achieving low-noise performance.