Methods and systems for calculating a corrected Fractional Flow Reserve. Methods include delivering a pressure sensing device including a pressure sensor to a location in an artery having a stenosis, positioning the pressure sensor distal to the stenosis, measuring the distal pressure, measuring the proximal pressure, and calculating a corrected Fractional Flow Reserve using the measured proximal and distal pressures and applying a correction factor or correction equation. The correction factor or correction equation corrects for changes in the measured distal pressure caused by a presence of the pressure sensing device. A data set of correction factors or correction equations may be stored in a memory component of the system. The corrected Fractional Flow reserve may approximate the Fractional Flow Reserve that would be obtained if a different sized device was used to measure the distal pressure, such as a pressure sensing guidewire having a 0.014 inch outer diameter.
