A catheter includes an elongate shaft, a pressure sensor, and a thermistor. The elongate shaft defines a guidewire lumen. The pressure sensor is coupled to a distal portion of the elongated shaft such that the pressure sensor senses a blood pressure distal of a stenosis. The thermistor is coupled to the distal portion of the elongate shaft such that the thermistor measures blood flow velocity distal of the stenosis. The pressure sensor and thermistor are in communication with a processor. The processor calculates a corrected Fractional Flow Reserve including a correction based on blood flow velocity.
