CCDS: Physical principles and technical considerations
CCDS (color-coded Doppler sonography — also referred to as color Doppler ultrasound or CDU) is a combined ultrasound modality offering blood flow information superimposed on a gray scale picture. Areas within the image which contain flowing blood (or other moving or vibrating tissue or particles — a potential source of artifact) are assigned color-overlay information based on a number of parameters including direction of flow, mean flow velocity, and velocity variance (which can be an indicator of turbulence). Flow toward the transducer is generally encoded as red, flow away from the probe as blue. As velocity increases the assigned color becomes lighter in shade; this often referred to as “color fading” or “decreased color saturation” (Figs. 2, 3). Many CCDS instruments allow introduction of additional color (often green or orange) in areas where marked variation in velocity is encountered (Fig. 9); this can help visually “flag” regions of turbulent flow as are often encountered just distal to an area of stenosis.
KeywordsGray Scale Color Noise Doppler Shift Frequency Color Display Doppler Data
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