Synonyms

Scintillation artifact, twinkle artifact.

Definition

Twinkling artifact is a color phenomenon visible behind a strongly reflecting interface such as urinary tract stones, parenchymal calcification or bones during color Doppler examination. It manifests itself as a color signal but without real flow behind the structures. It imitates turbulent flow.

This artifact has been described behind calcifications in various tissues.

Etiology

Twinkle artifact occurs behind highly reflective objects, particularly urinary tract stones [1, 2]. Earlier authors believed that this artifact was dependent on surface roughness [4]. Some newer articles describe this artifact as a phenomenon dependent on ultrasound machine settings (color-write priority, gray-scale gain, and pulse repetition frequency), motion of the object scanned with respect to the transducer, and equipment used [2].

Presence of this artifact is sometimes beneficial, such as in cases of detection of urinary tract stones with indistinct echogenicity and poor posterior acoustic shadowing. In some studies the twinkling artifact was present in 83% of urinary stones [2].  That is why it can be used as one of the diagnostic criteria for urinary calculi.
However, twinkling artifact can also be a source of confusion. For example, in prenatal fetal scans it can imitate aberrant vessels or flows behind echogenic structures or give the impression of cardiac activity in fetal demise. (See the Pitfalls & Artifacts lecture for some video clips on the subject).

Because this artifact is dependent on ultrasound machine settings it is possible to distinguish it from real vessels by changing some parameters. For instance, when the focal zone is above the source of the artifact (such as a urinary stone) the artifact disappears, but when the focal zone is under the hyperechoic area it occurs [2]. This could be an easy distinguishing maneuver in assessment of this phenomenon.

Pictures 1, 2, 3, 4: Presence of twinkling artifact in dead fetus.

References