Pulmonary angiography using intravenous rather than intra-arterial injections and digital subtraction technique provides an alternative to dependence on clinical impression, lung scans, and the more invasive transcardiac selective pulmonary angiogram for the diagnosis of pulmonary embolism. However, successful studies of the pulmonary circulation using IV-DSA require careful preselection of patients and meticulous attention to technical detail, as well as a state-of-the-art digital imaging system.