Figure 5.

Reconstruction of retrospectively rate-4 undersampled images from computer-simulated phantoms that undergo translational shifts, rotation, deformation/TPM and variable signal intensity over time. Example reconstructed images at one time frame are shown in the top row. Phantom 1 (P1) undergoes rigid translational shifts along the phase-encoding direction. P2 has an abrupt change in size as well as appearance/disappearance of features to mimic through plane motion combined with translational shifts in the readout direction. P3 undergoes rigid translational shifts along the readout direction. P4 undergoes a gradual change in size which can be interpreted as either cardiac contraction or through-plane motion. P5 rotates counterclockwise through time to mimic object rotation motion. All the phantoms also have quadratically changing signal intensity over time. Corresponding x-t profiles for each phantom (P1–P5) are shown on the bottom panel, where the profile locations are indicated by dashed lines on the fully-sampled image. The first column shows fully-sampled data reconstructed by FFT and serves as a reference. The other columns display undersampled data reconstructed using conventional FFT and the CS methods: BLOSM, k-t FOCUSS with ME/MC, k-t SLR, BLOSM without motion guidance (BLOSM w/o MG) and k-t SLR with global motion guidance (k-t SLR w/ gMG). BLOSM provided the most accurate recovery of the fully sampled images. For k-t FOUCSS with ME/MC, k-t SLR and BLOSM w/o MG, residual artifacts and moderate motion blurring can be observed, especially on P4.