BACKGROUNDOptical coherence tomography (OCT) is a new imaging technique capable of obtaining high-resolution intravascular images of small vessels and has been widely used in interventional cardiology. However, application of OCT in peripheral pulmonary arteries in patients has been seldom documented.

METHODSThree patients who were highly suspected peripheral pulmonary arteries thrombi and had undergone CT pulmonary angiography but tested negative for thrombi in peripheral pulmonary arteries were enrolled. Subsequently, OCT imaging was performed in peripheral pulmonary arteries. The patients received more than three-month anticoagulative treatment if thrombi were detected by OCT. Thereafter, OCT re-evaluation of the thrombolized blood vessels detected earlier was performed. The changes of thrombi before and after anticoagulative treatment were compared.

RESULTSThree patients underwent OCT imaging of peripheral pulmonary arteries. Thrombi were found in most of imaged vessels in these patients. Red and white thrombi can be differentiated, according to features of the thrombus on OCT images. After anticoagulation treatment, these patients' symptoms and hypoxemia improved. Repeated OCT imaging showed that most thrombi disappeared or became smaller.

CONCLUSIONOCT may be used as a potential tool for detecting peripheral pulmonary artery thrombi and differentiating red thrombi from white ones.