Angiography is not a screening examination, and is reserved for those patient's with a higher probability of disease and for preoperative planning. Indirect signs of these can be demonstrated on plain radiographs by evaluating for cardiac contour abnormality. However, congenital heart disease is better screened with echocardiography rather than chest radiographs. A common congenital anomaly is tetralogy of Fallot in which there is decreased pulmonary perfusion due to pulmonary artery stenosis. The tetralogy includes ventricular septal defect, right ventricular outflow obstruction, right ventricular hypertrophy, and an overriding aorta.
Plain radiographs are usually negative in a patient with pulmonary embolism.
These findings are uncommon. The most common scenario is a patient presenting with an unexplained shortness of breath with a normal chest radiograph. Two large areas of mismatch are considered high probability for pulmonary embolus. No perfusion defects are considered normal and very small areas of abnormality are considered low probability. Essentially, the rest is considered intermediate or indeterminate.