Color Doppler Imaging

Being a core function of all modern multipurpose ultrasound devices, color Doppler imaging (CDI) has many indications in ophthalmology. In this chapter, we discuss the theory and the technique to obtain the best morphological and functional information. After describing the Doppler effect, this chapter presents the different Doppler modes, with an illustration for each. The first is the continuous Doppler, the oldest in vascular medicine, exploring vessels “blindly” without an associated imaging system, studying only the sounds and hence, not suitable for ophthalmological applications. For pulsed Doppler, with different representations, in the color mode, the images of the flows are superimposed on a B-image according to a color scale, translating the pulse repetition frequency, which must be adapted to the slow flows characteristic of ophthalmology and tailored when the settings are responsible of aliasing and blooming artifacts. In the spectral mode, which is the quantitative mode, the resistive index gives an idea of the flow for these vessels whose diameter is not known. Afterwards, we discuss the power Doppler, which is unfortunately sensitive to movements. Finally, we review micro-Doppler/B-flow/smi/mvi which is a new method of vascular ultrasound independent of the Doppler effect, with no blooming or aliasing, which seems promising in ophthalmology.