Presentation
Patient presented to the emergency department with severe pain in right flank.
Patient Data
An echogenic calculus of size 7.1 mm in right vesicoureteric junction, with comet-tail twinkling artifact posterior to the calculus, on color Doppler.
No posterior acoustic shadowing is seen.
Normal left ureteric jet is seen.
Arrow points to comet-tail twinkling artifact posterior to the calculus, on color Doppler posterior to right vesicoureteric junction stone.
Case Discussion
The use of twinkling artifact can aid in the diagnosis of urinary calculi which do not show posterior acoustic shadowing 1.
This artifact is due intrinsic noise called phase (or clock) jitter within the Doppler circuitry of the US machine. It is seen as a focus of alternating colors, often in the shape of a comet-tail 2.