The sign refers to a tail of soft tissue extending from a calcification, representing the collapsed / scarred / thrombosed parent vein. When well seen it is said to have a positive predictive value of 100% 1.
- 1. Guest AR, Cohan RH, Korobkin M et-al. Assessment of the clinical utility of the rim and comet-tail signs in differentiating ureteral stones from phleboliths. AJR Am J Roentgenol. 2001;177 (6): 1285-91. AJR Am J Roentgenol (full text) - Pubmed citation
- 2. Dyer RB, Chen MY, Zagoria RJ. Classic signs in uroradiology. Radiographics. 2004;24 Suppl 1 (suppl 1): S247-80. Radiographics (full text) - doi:10.1148/rg.24si045509 - Pubmed citation