Clinical Significance of Twinkling Artifact in the Diagnosis of Urinary Stones

Abstract

The twinkling artifact is a color Doppler artifact, but it could be used in the confirmation of urinary stones. Conventionally, gray-scale criteria (echogenic foci with acoustic shadowing) is used in the diagnosis of urinary stones, but unfortunately, its reliability is very low. If the color Doppler twinkling artifact is applied in conjunction with other provocative measures, then its overall reliability exceeds 95%. To determine the clinical significance of twinkling artifact in the diagnosis of urinary stones, this cross-sectional observational study was conducted at Gilani Ultrasound Center, Lahore, Pakistan. For the determination of clinical significance, 1350 patients were recruited for this study. All the patients had renal stones of variable size and location. All the patients were evaluated with gray-scale sonographic criteria, and then color Doppler was applied to look for the twinkling artifact. The findings were confirmed with other imaging modalities (i.e., plain X-ray, computed tomography scan, etc., or during patient follow up). Sensitivity and specificity of the gray-scale ultrasound criteria in the detection of urinary stones was 96.1% and 57.9%, respectively, while the sensitivity and specificity of the color Doppler twinkling artifact in the detection of urinary stones was 100.0% and 97.4%, respectively. It was concluded that the application of twinkling artifact is useful in the confirmation of urinary stones, but specifically, it is of great diagnostic value in the small (less than 5 mm) renal stones and stones adjacent to a strong reflector (i.e., ureteric stones or stones in the prostatic urethra).

Keywords: Acoustic shadowing; Renal stone; Twinkling artifact; Ureteric stone; Urinary stone.