what do you see?
The signet ring sign is present on the xray.
The signet ring sign can be seen in the scaphoid when it demonstrates a cortical ring as a result of foreshortening on a PA projection. This suggest volar rotation of the scaphoid with scapholunate dissociation. It can occur in normal wrists if the xray is taken with the wrist flexed. If this happens the lunate would appear more triangular as it would be flexed as well.
In addition to the signet ring of the Game of Thrones and the signet ring of the scapholunate dissociation, the ring can be see in bronchiectasis and papillary necrosis. The signet ring can be seen in bronchiectasis when the dilated bronchus and pulmonary artery branch are seen in cross section. Normally, the bronchus and pulmonary artery branch are the same size but in bronchiectasis the bronchus is much larger.
The signet ring appearance can also be seen in an IVP with renal papillary necrosis where contrast fills the circumferential fornix of the necrotic papillae.
Abe T, Doi K, Hattori Y. the clinical significance of the scaphoid ring sign: a study of normal wrist xrays. 2008. Journal of Hand surgery, https://doi.org/10.2277/1753193407087572.
Ouellette H, the signet ring sign. Radiology. 1999;212(1):67-8Doi:10.1148/radiology.212.1.r99jl2067
Burgener F, Kornano M,Pudas T. differential Diagnosis in conventional Roadiology. Thieme. (2008) ISBN:1588902757
Jung D, Kim S, Jung S et al. Renal papillary necrosis: review and comparison of findings at multi-detector row CT and intravenous urography. Radiographics. 26(6): 1827-36.