Devices and methods for vascular navigation, assessment and/or diagnosis are described which determine the location of the tip of a vascular catheter using the introduction of a medium with a measurable parameter (e.g., temperature, light reflection, sound reflection, etc.) and sensing and measuring the measurable parameter as the catheter is advanced. Measurements of the parameter are tracked over time, recorded and analyzed. The value of the parameter and/or the shape of the parameter value vs. time curve may be used in the analysis. For example, curve amplitude, variability, standard deviation, slope, etc. may be used in the analysis of catheter location.