Informativeness of the doppler twinkling artifact in the diagnosis of urinary tract calculi

Abstract

The kidney stone disease (nephrolithiasis, urolithiasis) is a common urological problem that affects both adults and children and has a high recurrence rate. Early and reliable imaging diagnosis of urolithiasis is important for early pain relief and the avoidance of complications that require surgical intervention. Non-contrast computed tomography is considered the method of choice in the diagnosis of urolithiasis, however, this method is associated with exposure to ionizing radiation. Ultrasound diagnostics or sonography, in contrast, is considered as the method of early diagnosis of urolithiasis that is widely spread, highly accessible and does not use ionizing radiation. Recently, the attention of sonographers has been attracted by the so-called twinkling artifact or the artifact of the colored comet tail, which occurs in the Doppler color flow mapping behind a calculus in the urinary tract. The twinkling artifact is a phenomenon of a rapid change (twinkle) of red and blue behind the calculus. Among adult patients, the artifact shows high sensitivity in finding urinary stones, but at the same time a high level of false-positive results. However, the sensitivity of the artifact in children is higher than in adults, whereas the rate of false-positive findings is much lower. According to many authors, the sensitivity and specificity of the twinkling artifact as an independent diagnostic sign of urolithiasis are both very heterogeneous, especially compared to non-contrast computed tomography. Nevertheless, the artifact is known to increase the diagnostic efficiency in stone detection to more than 90%. We believe that the twinkling artifact in the Doppler color flow mapping should always be considered as an additional diagnostic tool, which is complementary to B-mode ultrasonography and increases its sensitivity and specificity.