_Comet tail sign in non contast CT - Phleboliths
The ‘comet tail’ sign refers to an adjacent, often irregular and eccentric tapering soft tissue mass corresponding to the non-calcified portion of the vein associated with a phlebolith.
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%.
In the image, A soft tissue rim sign is present around an impacted right distal ureteric stone (arrow). A comet tail sign is present adjacent to a pelvic phlebolith (dashed arrow). The comet tail does not surround the phlebolith. Each suspicious calcific focus should be separately assessed for these signs._
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%.
In the image, A soft tissue rim sign is present around an impacted right distal ureteric stone (arrow). A comet tail sign is present adjacent to a pelvic phlebolith (dashed arrow). The comet tail does not surround the phlebolith. Each suspicious calcific focus should be separately assessed for these signs._