Glass foreign body
Glass foreign bodies may be present if they are ingested, inserted, or as a result of an injury. All glass is radiopaque 7.
The prevalence of glass foreign bodies in wounds from injury has been recorded at a rate of 1.5% in superficial (subcutaneous) wounds and 7.5% of deeper wounds 1. They make up ~15% (range 9-24%) of all retained foreign bodies 10.
Only ~10% of x-rays ordered for investigation of retained foreign bodies are positive (reflecting the low incidence post-injury), but x-rays are excellent at detecting radiopaque foreign bodies with ~85% being detected 6:
- glass is always radiopaque, independent of lead content or other additives, with the caveat that tiny pieces may be too small to actually be resolved (see below) 7,8
- should be visible on plain films if larger than 2 mm 2,5,10
All glass is visible on CT and usually easier to see than on plain radiography 9. Density varies between 500-1900 HU. Dense fragments as small as 0.01 mm3 can be detected 10.
- can be used to localize foreign bodies further and define the relationship with soft tissue structures and assess for further injuries
- appears hyperechoic with posterior acoustic shadowing and often demonstrates reverberation artifact 10
- if present for >24 hours may demonstrate a hypoechoic ring 3,4
MRI would clearly not be the first choice investigation for detecting foreign bodies, including glass. Nevertheless, on MRI all forms of glass are seen but on most sequences considerable artifact is present 9.
- T1: low signal
- T2: low signal
- T2*: blooming artifact
- T1C+: linear enhancement if a foreign body granuloma has formed 10
- 1. Orlinsky M, Bright AA. The utility of routine x-rays in all glass-caused wounds. Am J Emerg Med. 2006;24 (2): 233-6. doi:10.1016/j.ajem.2005.06.008 - Pubmed citation
- 2. Hunter T, Taljanovic M. Radiographics. 2003;23 (3): . doi:10.1148/rg.233025137
- 3. Boyse TD, Fessell DP, Jacobson JA et-al. US of soft-tissue foreign bodies and associated complications with surgical correlation. Radiographics. 2001;21 (5): 1251-6. Pubmed citation
- 4. Horton LK, Jacobson JA, Powell A et-al. Sonography and radiography of soft-tissue foreign bodies. AJR Am J Roentgenol. 2001;176 (5): 1155-9. doi:10.2214/ajr.176.5.1761155 - Pubmed citation
- 5. Halaas GW. Management of foreign bodies in the skin. Am Fam Physician. 2007;76 (5): 683-8. Pubmed citation
- 6. Cambridge textbook of accident and emergency medicine. Cambridge University Press. ISBN:0521433797. Read it at Google Books - Find it at Amazon
- 7. Klein KA, Hobbs BB. Radiopacity of glass: does the lead content matter?. (1995) CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne. 153 (9): 1224. Pubmed
- 8. Aras MH, Miloglu O, Barutcugil C, Kantarci M, Ozcan E, Harorli A. Comparison of the sensitivity for detecting foreign bodies among conventional plain radiography, computed tomography and ultrasonography. (2010) Dento maxillo facial radiology. 39 (2): 72-8. doi:10.1259/dmfr/68589458 - Pubmed
- 9. Ingraham CR, Mannelli L, Robinson JD, Linnau KF. Radiology of foreign bodies: how do we image them?. (2015) Emergency radiology. 22 (4): 425-30. doi:10.1007/s10140-015-1294-9 - Pubmed
- 10. Bruno C. Carneiro, Isabela A. N. Cruz, Renan N. Chemin, Thiago A. Rizzetto, Júlio B. Guimarães, Flávio D. Silva, Ciro Yoshida Junior, Daniel Pastore, Alípio G. Ormond Filho, Marcelo A. C. Nico. Multimodality Imaging of Foreign Bodies: New Insights into Old Challenges. (2020) RadioGraphics. doi:10.1148/rg.2020200061