Synthetic 32-channel contrast phantom, with 0.25% and 0.1% complex Gaussian noise added, R = 12.1 uniformly undersampled, and reconstructed using (a) GRAPPA, (b) GRAPPA with multichannel adaptive local Wiener filter-based denoising, (c) L1 SPIR-iT, and (d) DESIGN denoising, with a four-level ‘9-7’ DWT sparsifying transform. The magnitude difference images shown and the PSNR are relative to the original noise-free synthetic image.