Figure 7.

Performance comparisons with R = 10.5, 10.5, and 12.4 uniform undersampling, for these three datasets, respectively, repeated using the identity matrix in place of the measured noise covariance. For the representative slices from each dataset, the magnitude and difference images of a representative region are shown, along with PSNR, for (a) GRAPPA, (b) GRAPPA with multichannel adaptive local Wiener-filter-based denoising, (c) L₁ SPIR-iT, and (d) DESIGN denoising. The choices of λ were established based on coarse, then fine, parameter sweeps for each dataset independently.