Stimulated emission depletion (STED), widely used in fluorescence microscopy with a key donut-shaped PSF, is rarely appliedtootherbiomedicalimaging. Magneticparticleimaging(MPI),anon-ionizingtechniquefordetecting magnetic nanoparticles, has Gaussian PSF (from field-free line/FFL harmonic signals) with limited resolution. Theimaginary part of a point source’s harmonic signal in MPI can form a donut-shaped PSF. Based on difference of Gaussian (DoG) theory, subtracting this donut PSF from Gaussian PSF yields a STED PSF with 3–4x higher resolution. In human brain FFL-MPI simulation, STED acquired donut-PSF projected signals, and super-resolution images were reconstructed via 1D deconvolution, filtered backprojection, or Richardson–Lucy with total-variation regularization.
Jia et al. (Sun,) studied this question.