Systems and methods are disclosed for diagnosing and treatment planning for vascular steal syndromes and retrograde flow. One method includes receiving a reference blood flow direction at a location in a reference vasculature determining a patient-related blood flow direction at a location in a patients vasculature corresponding to the location in the reference vasculature determining a difference in direction, between the reference blood flow direction of the reference vasculature and the patient-related blood flow direction of the patients vasculature and generating a representation of the location in the patients vasculature associated with the difference in direction between the reference blood flow direction and the patient-related blood flow direction, or generating a treatment recommendation for the patients vasculature based on the difference in direction between the reference blood flow direction and the patient-related blood flow direction.
