Non-Cartesian imaging#
Radial and spiral trajectories sample k-space off the Cartesian grid. Their Fourier transform is a non-uniform FFT (NUFFT), their adjoint approximates an inverse only after density compensation, and the normal operator of an iterative reconstruction becomes a convolution with the point spread function of the trajectory. This section introduces trajectories, the NUFFT, density compensation and the point spread function; reconstructs an undersampled golden-angle radial acquisition by non-Cartesian SENSE, with coil sensitivities estimated from the radial data; and reconstructs a continuous golden-angle acquisition as a time series with a temporal regularizer. Non-Cartesian sampling defines the transform and its accuracy.
