(CAI) Color amplitude imaging shows the amplitude of the Doppler signal from moving blood flow. CAI is an ultrasound technique with increased dynamic range and flow sensitivity. The sensitivity of Doppler ultrasound increases markedly in conjunction with the use of vascular contrast agents.

See also Amplitude Map, Amplitude Indicator.

The amplitude is the signal height. The amplitude of the ultrasound echo is proportional to the difference of the acoustical impedance caused by different tissue layers. The amplitude decreases with increasing penetration depth of a homogeneous tissue.

See also Color Amplitude Imaging.

The Doppler signal from any range gate is proportional to the number of red blood cells moving through during the periods of its read out, so the amplitude (or loudness) works as an indicator of the number of blood cell reflectors.
High Doppler amplitudes are generated by large pulsed Doppler or color Doppler imaging range gates and large vessels.

See also Amplitude Map, Color Amplitude Imaging.

(CFI) Color flow imaging is based on pulsed ultrasound Doppler technology. With this technique multiple sample volumes among multiple planes are detected and a color map for direction and velocity flow data is displayed.
Common mapping formats are BART (Blue Away, Red Towards) or RABT (Red Away, Blue Towards). Enhanced or variance flow maps show saturations and intensities that indicate higher velocities and turbulence or acceleration. Some maps utilize a third color (green) to indicate accelerating velocities and turbulence.
Color flow Doppler imaging is not as precise as conventional Doppler and is best used to scan a larger area and then use other Doppler modes to obtain more precise data.

See also Color Amplitude Imaging, Color Priority, and Color Saturation.

In a color map, colors are allocated to Doppler shift frequencies corresponding to flow. Color (colour, Brit.) maps may also display Doppler amplitude, signal power, variance, or the gray levels of the B-mode image.

See also Color Amplitude Imaging, Color Priority, and Color Saturation.