FIG. 2.

Illustration of phase sorting process with result-driven strategy. For illustration purposes, the total number of slices is set to be 8 and the total number of respiratory phase bins was set to be 6. Sequential acquisition mode is used to repeatedly (labeled as repetition no.) acquire 2D MRI images for volume of interest. Slice location information and respiratory signal are recorded with image acquisition. Red S-number is the slice location index for each 2D MR image, and respiratory phase is calculated accordingly. The sorting process is illustrated on slice 1 as an example. Seven images for slice 1 from seven repetitions come from different respiratory phases. Each of them is assigned to a phase bin. Result-driven strategy is applied to the phase bin with redundant images. The one with minimum amplitude error as compared with average breathing curve will be selected as a component of the 4D dataset.