[Significance of technical parameters in color-coded duplex ultrasound for vascular studies]

Reliable colour-coded ultrasound duplex investigations of the vascular system require sufficient knowledge of its technical features. The most important parameters are the emitted ultrasound frequency, the axial and lateral resolution, the relationship between the colour-coded and B-mode gain, the Doppler insonation angle of the vessels, the upper (aliasing threshold) and lower (wall filter) cut-off frequencies, the frame rate as well as the influence of digital image processing. The practical relevance of these features for assessing the velocity, direction, pulsatility, localisation and disturbance of flow in blood vessels is discussed in comparison to conventional Doppler and duplex techniques.