Colorflow duplex ultrasonography is used to evaluate the arterial and venous systems. This technology combines three ultrasound modalities:

1. Two-dimensional B-mode ultrasound imaging of tissue in gray scale provides anatomic data about the vessels of interest. Utilizing this modality can determine the presence or absence of atherosclerotic plaque or thrombus.
2. Doppler ultrasound provides physiologic data about blood flow in the vessel. By utilizing this modality, a Doppler velocity spectral analysis is obtained, that can determine whether plaque or thrombus is hemodynamically significant and compromising blood flow.
3. Colorflow ultrasound provides the ability to quickly visualize blood flow and demonstrate the degree of vessel obstruction.