1. A computer-implemented method of assessing a risk of disease, the method comprising: obtaining an anatomic model associated with a target anatomy; modeling, using a processor, an injection of one or more virtual contrast agents into the anatomic model; determining a plurality of locations of the anatomic model; performing a fluid dynamics simulation of a flow of blood and the one or more virtual contrast agents through the determined plurality of locations of the anatomic model; computing one or more values of concentration of the one or more virtual contrast agents at the determined plurality of locations in the anatomic model based on the fluid dynamics simulation; and determining one or more simulation-based diagnostic flow metrics from the values of concentration of the one or more virtual contrast agents computed at the determined plurality of locations in the anatomic model, based on the fluid dynamics simulation.