Systemic air embolism after percutaneous computed tomography (CT)-guided lung biopsy is very rare. The estimated incidence is 0.061–0.21% [
1,
2], but could be underestimated because of failure to diagnose this adverse event in asymptomatic patients [
3]. For example, in a study published in 2012, Freund et al. found that the incidence of radiologically proven systemic air embolism was 3.8%, whereas the incidence of clinically apparent systemic air embolism was 0.49% [
4]. Thus, the incidence of post-biopsy systemic air embolism might be higher than is estimated, and sequential CT scans of the entire thorax instead of only the biopsy area might be worth performing to provide a definitive diagnosis of systemic air embolism [
5]. Generally, systemic air embolism is thought to occur via two mechanisms. First, if the tip of the biopsy needle is lodged in a pulmonary vein and the inner stylet is removed, air embolism occurs during rapid inspiration when atmospheric pressure exceeds pulmonary venous pressure. Second, when the needle simultaneously traverses an air-containing space and adjacent pulmonary vein, a fistula can occur, resulting in air entering the pulmonary vein when the alveolar pressure is greater than the pulmonary venous pressure [
6]. Air can enter via a fistula tract, connecting an air-containing space to a pulmonary vein when alveolar pressure is high, for example, during coughing. To prevent air embolism, the introducer needle should always be occluded by the inner stylet, saline drops, or the operator’s finger. Moreover, the patient should be instructed to avoid breathing deeply or coughing forcefully during the procedure [
7,
8]. It is believed that, following lung biopsy and needle withdrawal, a large number of alveolar-venous or bronchial-venous fistulas can develop along the needle’s trajectory. During vascular injury, the walls of small vessels are usually retracted; spontaneous adhesion occurs, forming a seal. When a patient exhibits any symptoms suggestive of air embolism during the lung biopsy procedure, the needle should immediately be removed [
8,
9]. The clinical manifestations of air embolism vary, depending on the exact location of the arterial embolus and the volume of air disseminated into the vessels. Once air enters the systemic circulation, it will enter the respective arterial end beds [
1,
8]. Functional end arteries can be occluded by even a small volume of air. Only 2 mL of air injected directly into the cerebral circulation is enough to be fatal, and 0.5–1.0 mL of air injected into a coronary artery can lead to cardiac arrest [
10]. Initial management includes immediate administration of 100% oxygen and placing the patient in a slight Trendelenburg position [
7]. Early hyperbaric oxygen therapy is recommended for patients with cerebral air embolism [
5].
Previously reported cases have only demonstrated imaging findings as existing air emboli in post-procedure CT scans. Imaging findings at different times, and the use of those findings to track the course and resolution of air emboli, have not been described. We report a case of systemic air embolism after CT-guided biopsy due to a kink in the coaxial biopsy system, and show the course followed by the emboli, demonstrated on sequential CT scans.