Color Doppler twinkling artifact in hyperechoic regions.

PURPOSE: To investigate a new color Doppler ultrasound (US) artifact that manifested as a rapidly changing mixture of red and blue behind a strongly reflecting structure. MATERIALS AND METHODS: In 140 consecutive patients with parenchymal calcifications seen at US, the presence of color signal was assessed in calcified areas relative to adjacent noncalcified tissue. The artifact, called the twinkling color artifact, was stimulated with various strongly reflecting structures immersed in still water. RESULTS: The artifact was found in 42 parenchymal calcifications. In vitro experiments showed that the twinkling artifact was present in granular structures, whereas no color signal was noted in smooth surfaces. The "twinkling sign" appeared to be generated by a strongly reflecting medium composed of individual reflectors. CONCLUSION: The presence of a color signal close to calcifications should be interpreted with caution, and a flow spectrum should always be recorded to eliminate the twinkling artifact.