The use of radioisotope techniques for the diagnosis of obstructive airway disease

Perfusion scintigraphy, radioaerosol inhalation scintigraphy, 133Xe studies and sup(81m)Kr studies are useful radioisotope techniques for the detection of regional pulmonary abnormalities in obstructive airway disease. The patient during asthmatic attack shows the perfusion defects with indefinite boundary, which may change during the following several days. Decreased ventilation are seen on the regions with perfusion defects, and ventilatory defects are more marked than those of perfusion. On the other hand, these abnomal findings is reversible. In chronic emphysema or chronic bronchitis, the regions with decreased perfusion usually cannot be correlated with any specific segments, and scintigraphys done repeatedly fail to show re-vascularization on the regions. In the radioaerosol inhalation scintigraphy, deposition pattern reveal the severity of COPD. In addition, xenon studies in the diseases show marked or moderate prolongation of wash-out from the abnormal region, and the abnormalities of ventilation are equal to or exceed the abnormalities of perfusion. (author)