Radioisotope scanning of the lungs is an easy and effective way to diagnose pulmonary thromboembolic disease. It is safe, repeatable, and highly accurate, according to Henry N. Wagner, Jr., MD, Johns Hopkins University School of Medicine, Baltimore.
Variations in blood supply to regions of the lungs have been measured, until recently, by pulmonary arteriography or radioactive gas techniques. Arteriography requires injection of large quantities of high density radiographic contrast media directly into the pulmonary artery. This necessitates cardiac catheterization, mechanized injection equipment, and radiographic equipment which will expose x-ray film at high speed.
The procedure involves a certain risk to patients—particularly those with pulmonary hypertension, Wagner told The Journal, but this technique is definitely useful in determining whether obstructed blood flow involves the larger pulmonary vessels. Scintillation scanning may be used to screen patients for this procedure.
Radioactive xenon has been used to determine alterations in pulmonary blood flow by injecting