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Purpose: To develop a generic radial sampling scheme that combines theadvantages of golden ratio sampling with simplicity of equidistant angularpatterns. The irrational angle between consecutive spokes in golden ratio basedsampling schemes enables a flexible retrospective choice of temporalresolution, while preserving good coverage of k-space for each individual bin.Nevertheless, irrational increments prohibit precomputation of the point-spreadfunction (PSF), can lead to numerical problems, and require more complexprocessing steps. To avoid these problems, a new sampling scheme based on arational approximation of golden angles (RAGA) is developed.  Methods: The theoretical properties of RAGA sampling are mathematicallyderived. Sidelobe-to-peak ratios (SPR) are numerically computed and compared tothe corresponding golden ratio sampling schemes. The sampling scheme isimplemented in the BART toolbox and in a radial gradient-echo sequence.Feasibility is shown for quantitative imaging in a phantom and a cardiac scanof a healthy volunteer.  Results: RAGA sampling can accurately approximate golden ratio sampling andhas almost identical PSF and SPR. In contrast to golden ratio sampling, eachframe can be reconstructed with the same equidistant trajectory using differentsampling masks, and the angle of each acquired spoke can be encoded as a smallindex, which simplifies processing of the acquired data.  Conclusion: RAGA sampling provides the advantages of golden ratio samplingwhile simplifying data processing, rendering it a valuable tool for dynamic andquantitative MRI.

Rational Approximation of Golden Angles for Simple and Reproducible Radial Sampling