Fig. 3

Reconstructed images of a set of real four-channel axial brain data. The acquisition is accelerated with a net reduction factor of 2.56. a Reference image with SoS reconstruction. b GRAPPA reconstruction with 48 ACS lines and 4 outer reduction factor. c GRAPPA reconstruction with 22 ACS lines and 3 outer reduction factor. d Reconstruction using Tikhonov regularization. e Reconstruction using IRLS method. f Reconstruction using AV-GRAPPA. g–l Patches extracted from the same position in a–f, respectively. AV-GRAPPA is able to achieve high SNR while still keeping the image from blurring boundary. On the other hand, other methods reconstruct the image with noise more or less