Combination of Phased-Array Coil Signals in Localized 2D Correlated Spectroscopy: Artifacts and Remedies

Introduction & Purpose: Multi-channel phased-array radio-frequency (RF) coils are capable of acquiring several streams of acquisitions in parallel, resulting in improved signal-to-noise ratios (SNR) and faster scan times (1,2). Data streams from these coils must be added in-phase during coil combination or risk losing signal to phase cancellation. Conventional coil combination schemes work well in one-dimensional (1D) Magnetic Resonance Spectroscopy (MRS), aligning the phase from every measurement to an arbitrary but equal value for each coil (3). Extension of the same generates multiple artificial parallel diagonals in two-dimensional (2D) localized correlated spectroscopy (L-COSY) (4), possibly due to the loss of phase information during coil combination resulting in artificial phase offsets along the F2 dimension. A major goal of this study was to investigate the source of these artifacts and develop an optimal algorithm to combine multi-channel RF coil-acquired 2D L-COSY data.