Fig. 17

Sequential axial CT images (a–f) from a test bolus obtained at the level of main pulmonary artery. Notice the altered pattern of contrast flow. In a normal patient, contrast injected from the upper extremity first opacifies the SVC, followed by the right atrium, right ventricle, pulmonary artery, pulmonary vein, left atrium, left ventricle, ascending aorta, and finally the descending thoracic aorta. In this case we see an altered pattern of contrast flow: first SVC, followed by minimal opacification of the pulmonary artery and ascending aorta, dense opacification of the descending aorta followed by dense opacification of the ascending aorta. There is insufficient opacification of the pulmonary circulation due to siphoning of contrast by ECMO