The development of 300 mT/m gradients has opened new opportunities for exploring much shorter echo times (TE) in human diffusion imaging. Here, to further shorten TE, we developed a robust pulse-gradient spin-echo sequence with single-shot spiral readout on this hardware. The ultra-strong gradients induced vibrations, which were addressed by hardware modifications, while challenges posed by B0-inhomogeneity, eddy currents (captured using a field camera) and gradient-nonlinearity were addressed using iterative reconstructions. With this combination, for a b-value of 1000 s/mm2, we achieved TE = 21.7 ms. In this previously unchartered domain, we demonstrated enhanced sensitivity to myelin in spin-echo diffusion MRI.