The PSNR (left) and SSIM (right) bar plots from the three subjects (S1, S2 and S3) based on eight datasets, in the scenarios of 3-times sparse-sampling(1.8 min scan) and 6-times sparse-sampling(0.9 min scan). The Wilcoxon signed-rank test was performed between the anatomically constrained (AC) penalized reconstruction and the proposed reconstruction method. Correspondingly, *, **, and ns, located at the top of each bar plot, represents p-value<0.05, p-value <0.01, and non-significant, respectively.