PULMONARY embolism cannot be diagnosed on clinical grounds; it can only be suspected. In addition, pulmonary embolism often develops in patients who have other conditions that could explain some or all of the symptoms. For example, viral pneumonia may produce symptoms remarkably similar to those of pulmonary embolism. Additional testing is therefore needed to identify those patients who actually do have embolic disease.
Angiography is the gold standard for diagnosis, but this invasive test is associated with risk factors of its own. Thus, the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) investigators wisely sought a less invasive method to determine which patients could be spared the risk of angiography. Specifically, they studied the current role of ventilation/perfusion (Ve/Pe) scanning in the diagnosis of pulmonary embolic disease.
When these investigators issued their report, they stressed that for the best results, Ve/Pe scan findings should be combined with an assessment of the
Roger C. Bone. The Low-Probability Lung ScanA Potentially Lethal Reading. Arch Intern Med. 1993;153(23):2621–2622. doi:10.1001/archinte.1993.00410230023004