The present disclosure provides systems and methods for the determining a rate of change of one or more analyte concentrations in a target using non invasive non contact imaging techniques such as OCT. Generally, OCT data is acquired and optical information is extracted from OCT scans to quantitatively determine a flow rate of fluid in the target; angiography is also performed using one or more fast scanning methods to determine a concentration of one or more analytes. Both calculations can provide a means to determine a change in rate of an analyte over time. Example methods and systems of the disclosure may be used in assessing metabolism of a tissue, where oxygen is the analyte detected, or other functional states, and be generally used for the diagnosis, monitoring and treatment of disease.