RAPID: a routine assurance pipeline for imaging of diffusion.

Despite the widespread adoption of diffusion MRI techniques, there is still no consensus on a comprehensive quality assurance routine specific for diffusion acquisitions. We propose here a routine assurance pipeline for imaging of diffusion. The routine simply comprises diffusion-weighted acquisitions on a phantom; each repetition lasts less than 5 min and can be performed using a variety of isotropic test liquids. The proposed QA script checks for the linearity of G, the uniformity of Gmax across the field-of-view, the mutual agreement of gradient power across the three logical axes and the temporal stability. Optionally, the routine can correct for the mutual agreement of gradient power along the three axes, returning a set of gradient orientations to be used in data analysis. The effectiveness of the scheme in the presence of mismatched gradient amplitudes is reported using both simulations and in vivo data. The script is freely available online.