A 38-year-old woman with a 6-month history of breathlessness and intermittent central chest pain was referred for an ECG-gated cardiac CT examination. This excluded significant coronary artery disease, but revealed an unexpected extracardiac finding. The left pulmonary artery had an anomalous origin from the right main pulmonary artery and was seen to hook around and compress the right main bronchus before crossing to the left of the midline between the trachea and oesophagus to form a ring (fig 1). In addition, CT showed the proximal oesophagus to be mildly dilated (fig 2). The patient did not report any dysphagia on further questioning. Volume-rendered …