Systemic air embolism depicted on systematic whole thoracic CT acquisition after percutaneous lung biopsy: Incidence and risk factors

Objectives: To evaluate the incidence and risk factors of systemic air embolism (SAE) depicted on systematic whole thoracic CT performed after percutaneous lung biopsy. Methods: A total of 559 CT-guided lung biopsies performed between April 2014 and May 2016 were retrospectively evaluated. SAE was defined by the presence of air in the aorta or left cardiac cavities seen on whole thorax CT images acquired after needle withdrawal. Analyzed data focused on patient (age, sex, spirometry data, emphysema on CT, therapeutics received), target lesion (location, depth, size and feature) and procedure (patient position, length of intrapulmonary needle path, number of pleural passes and of biopsy samples, operator's experience). A regression logistic model was used to identify risk factors of SAE. Results: SAE was observed after 27 of the 559 lung biopsies, corresponding to a radiological incidence of 4.8% (95%CI: 3.3-7.0). Clinical incidence was 0.17% (n = 1). For 21/27 patients (78%), a targeted acquisition in the nodule area would not have included the cardiac cavities meaning SAE would have been missed. On multivariate analysis, the independent risk factors were needle path length through ventilated lung (OR: 1.13, 95%CI: 1.02-1.25, p = 0.024), number of samples (OR: 1.48, 95%CI: 1.01-2.17, p = 0.046) and prone position (OR: 3.12, 95%CI: 1.11-8.31, p = 0.031) or right-sided lateral decubitus (OR: 6.15, 95%CI: 1.66-22.85, p = 0.005). Conclusions: Asymptomatic systemic air embolism can be depicted in almost 5% of post biopsy CT examinations, when they are not limited to the targeted nodule area but include the entire thorax.