The use of an ultrasound, also called a sonogram, in medicine for diagnosis and preventive care has been common for decades. One limitation of traditional ultrasound images is that they are mostly only available as low-contrast, grayscale images. Color ultrasound represents a new development that uses collected data to add color to the image, both increasing contrast and making the image easier to interpret. Despite the way it sounds, color ultrasound does not depict the actual color of the area of the body being imaged, but rather assigns colors to certain detected patterns, in order to make them stand out from the rest of the image.
To avoid having the term "color ultrasound" misunderstood as an ultrasound in color, like a photograph, it is sometimes referred to as the color post-processing of an ultrasound. This term alludes to the fact that the color is added by a computer, and does not represent visible light reflections. It is usually considered to be a nonstandard technique, meaning that it is unusual except for certain circumstances.
When an ultrasound probe detects the echo of the waves it produces, it sends the data from that echo to a computer, which interprets the data as an image on its monitor. The differences in how the echo is reflected account for the different shapes and shades of gray displayed on the screen. The way that images are processed in a color ultrasound assigns colors to certain levels of echo reflection, to make them more visible. This adds a large amount of contrast and clarity, and can help confirm or suggest a diagnosis where it would not have been easy or possible to do so before.
One of the goals of color ultrasound is to advance the technology in such a way as to reduce the need for biopsies as a part of diagnosis. By making minute differences in tissues of the same area more visible, the cost of medical care may be reduced to the patient, as fewer diagnostic procedures may be needed. Most of the time, a doctor can interpret a grayscale ultrasound image correctly, but a color ultrasound makes the picture clearer. One common analogy used to describe color ultrasound is that we can tell what a traffic light is indicating by looking at differing levels of brightness and where they occur, but color-coding the lights helps remove any doubt. This is better, even for an experienced driver, just as a color ultrasound can clear things up, even for a highly trained physician.