Figure 1

K-space acquisition strategy: In regular 3D imaging, the profiles are acquired in either a linear (a) or radial ordering (b) fashion in the ky-kz plane. Based on the linear ordering, EPI acceleration divides the k-space into multiple segments (c), where one line from each segment is acquired within the same EPI shot. On the other hand, CS acceleration is mostly based on the radial ordering (d), where the k-space profiles are randomly undersampled and acquired in a radial fashion while keeping the center area of the k-space fully sampled. Both EPI and CS can be combined into one acquisition with a higher acceleration rate as shown in (e). While the k-space is divided into segments, each segment is randomly undersampled with the same pattern and then acquired in a radial fashion. The major advantage is the high overall acceleration rate (9 in this ex.) for the whole 3D acquisition, while one drawback is the necessity to fully sample parts of the k-space even if it is not at the center of the k-space.