How does patient motion typically appear on color Doppler imaging?

• A. A large flash of colors over a large tissue region
• B. Uniform color
• C. No color
• D. Sparse color speckle in the region of interest

Answer: (A)

Motion in color Doppler signals appears as a large, bright flash of color across a broad area because bulk tissue movement shifts Doppler signals from many nearby tissue parcels at once. This artifact isn’t real flow; true flow tends to be confined to vessels with coherent direction. So when a patient moves or the transducer shifts, the color display can suddenly illuminate a wide region, obscuring actual flow. The other patterns don’t fit this scenario: uniform color would imply consistent flow everywhere, no color means no Doppler signal, and sparse color speckle suggests only minor noise rather than a global motion artifact. To reduce it, have the patient stay still and adjust imaging settings like gain and wall filter.