Scaling nuFFT Memory-Overhead Down to Zero: Computational Trade-Offs and Memory-Efficient PICS-Reconstructions with BART

We propose a new decomposition of the nuFFT algorithm, allowing for a zero-memory-overhead implementation of the (adjoint-)nuFFT. With one grid-sized buffer, the decomposition allows for a memory efficient nuFFT with negligible computational overhead compared to a two-fold oversampled conventional nuFFT - to the prize of less efficient parallelization on many-threads CPU systems. We reduce memory requirements of 3D non-Cartesian PICS-reconstructions in BART by a factor up to ten, allowing for GPU acceleration of reconstructions with eight coils and matrix size 256x256x256 on a 4GB consumer-level GPU.