Figure 1:

Illustration of the differences in radial and Cartesian sampling. In (a), the Cartesian pattern captures parallel readout lines. The line is shown in (b) cross the central frequency and has a stronger signal, while the line shown in (c) captures the edge of the k-space and has a weaker signal. In (d), radial sampling always captures lines crossing the center of the k-space, so all k-space lines have stronger signals, as shown in (e)-(f).