While scanning a patient’s heart the other day, I noticed an artifact in the cine clips after adjusting the size of the color Doppler box. Let’s take a look.

The “color Doppler box” is the area of the screen over which movement is noticed by the machine and represented visually as color.

Standard color Doppler uses red and blue to indicate movement towards and away from the probe (not necessarily arterial vs venous). Power Doppler imaging, on the other hand, only uses shades of orange and has no directional information built into the color.

We use Doppler imaging for purposes of documenting the presence of blood flow in a testicle and identifying which structure in the portal triad is the hepatic artery, among others.

The size of the color Doppler box can be adjusted to fit the indication.

Below are four clips obtained on the same patient taken at the same time. The only change is the size of the Doppler box.

Example 1: No Color Doppler Box

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Example 2: Long and Narrow Color Doppler Box

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Example 3: Long and Wide Color Doppler Box

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Example 4: Very Long and Very Wide Color Doppler Box

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The Teaching Point

Notice that as we move from example 1 through example 4 the video gets much more choppy.

It is barely noticeable in example 2; it is obvious in example 3; and in example 4, it is distracting.

Adding color Doppler to your ultrasound requires a lot of processing power by the computer, and that power is finite. If you ask the computer to do more than it is capable of, something has to give – and in this case, we notice it as a decrease in the frame rate. As a result, the movement in the video clip no longer appears smooth.

If you need to use color Doppler, you should make the box as small as possible so that the detrimental effect on image quality is minimized.

Scan happy, my friends