FDG Embolism

Thrombus formation during intravenous administration of FDG can result in small pulmonary emboli that present as a focus (or foci) of intense FDG activity in the lung without a corresponding CT abnormality. These generally resolve after a few days and can even be seen to migrate peripherally in scans obtained on the same day.

The mechanism is thought to be related to FDG uptake by platelets at the site of injection and by neutrophils at the site of embolism. Vascular injury during FDG injection can lead to thrombus formation and platelet activation. Activated platelets have increased energy requirements and glucose uptake (5–6 times normal), which can lead to concentration of FDG in the thrombus. Activated neutrophils that respond to vascular injury after pulmonary embolism also have increased glucose uptake and can cause focal FDG uptake at the site of embolism.

References

• Farsad M, Ambrosini V, Nanni C, Castellucci P, Boschi S, Rubello D, Fabbri M, Franchi R, Fanti S. Focal lung uptake of 18F-fluorodeoxyglucose (18F-FDG) without computed tomography findings. Nucl Med Commun. 2005 Sep;26(9):827-30.
• Ha JM, Jeong SY, Seo YS, Kwon SY, Chong A, Oh JR, Song HC, Bom HS, Min JJ. Incidental focal F-18 FDG accumulation in lung parenchyma without abnormal CT findings. Ann Nucl Med. 2009 Aug;23(6):599-603.
• Kavanagh PV, Stevenson AW, Chen MY, Clark PB. Nonneoplastic diseases in the chest showing increased activity on FDG PET. AJR Am J Roentgenol. 2004 Oct;183(4):1133-41.