Axial CTA of the chest showing a saddle embolus with extension into the branches of the pulmonary artery.CTA was performed using Siemens SOMATOM Perspective 128 slices. Images were obtained in a cranio-caudal direction following contrast injection at 3mls/s. Contrast optimization was based on bolus tracking at the level of the main pulmonary artery using a trigger level of 100 HU.