Two schemes (Symmetric, Equatorial) for separating the k-space sphere into nested cones are possible for flexTPI. The nested cones can be symmetrically placed about the KX-KY plane (left, symmetric layout) such that there are no cones of radius KMAX (“equator” cone in KX-KY plane) or zero (“polar” cones lying along z-axis). Alternatively, the cones can be designed with equatorial and polar cones (right, equatorial layout). The two designs impose slightly different slew rate constraints. KMAX, the number of cones, and total number of projections depend on the acquisition FOV and matrix size.