Paradoxical air embolism following contrast material injection through power injectors in patients with a patent foramen ovale

In patients with a patent foramen ovale, use of air filters during intravenous infusions is common, but they are not compatible with power injection. Therefore we aimed to assess the incidence of paradoxical air embolism on CT of the chest and brain following contrast material injection through a power injector in patients with a patent foramen ovale, without the use of a filter. In this IRB approved, HIPAA compliant retrospective study, two independent radiologists reviewed 289 CT scans of the chest (n = 233) and brain (n = 56) for vascular air embolism following contrast material injection through a power injector in 93 subjects (43 men, mean age 66 y) with a known patent foramen ovale. The location and amount of the air were assessed. The medical records were reviewed for embolic symptoms. The prevalence and location of right sided and systemic luminal air were determined and inter-observer agreement for detection of intraluminal vascular air was calculated. Vascular air embolism was observed in 19.3% (56/ 289) of the studies; small in 52 and moderate in 4. In 42 studies, intravascular air was seen in a single territory and 14 studies had intravascular air in multiple territories. None had air in the left side of the heart or brain to suggest paradoxical air embolism. The inter-observer agreement for detection of vascular air was moderate (k = 0.6). Paradoxical air embolism in patients with a patent foramen ovale following contrast material injection with a power injector is rare.