Abstract: A method for imaging a substrate and product over time is provided. The substrate and product are magnetically tagged with at least one magnetic gradient where magnetically tagging provides a tag-dependent signal phase for the substrate and a different tag-dependent signal phase for the product. At least one readout of magnetically tagged substrate and product is provided over time. The tag-dependent signal phase is used to determine product that has been transformed from magnetically tagged substrate and substrate that has been transformed from magnetically tagged product over time.