Fig. 1

Test bolus technique for identification of contrast arrival in target vessel. Prolonged pulmonary circulation time in a patient with aortic stenosis. CT image during test bolus injection (a) with regions of interest over the ascending aorta (1), descending aorta (2) and pulmonary artery (3). Attenuation-time graph corresponding to the regions of interest (b) shows prolonged pulmonary circulation time of 16 s in this patient due to aortic stenosis (normal pulmonary transit time is approximately 7–9 s)