A time resolved, contrast-enhanced renal MRA exam. Images in the top row were acquired with a commercially available Cartesian TWIST sequence that utilizes Cartesian GRAPPA, view-sharing, and partial Fourier. Images in the bottom row were acquired with an undersampled stack-of-stars trajectory with an in-plane acceleration of 12.6 with respect to Nyquist, and reconstructed using a 3D through-time radial GRAPPA. Coronal subtracted MIP images for two neighboring time frames are shown for each of these acquisition/reconstruction methods. The spatial and temporal resolution of both datasets is nominally the same (3.5 s/frame, 1.5×1.5×3mm3). Note that the TWIST dataset has a temporal footprint of 17.5s, while the 3D through-time radial GRAPPA has a temporal footprint of 3.5s.