Krypton 81m ventilation scanning in chronic obstructive airways disease.

Ventilation and perfusion scans using 81Krm and 99Tcm-labelled macroaggregates have been studied in 60 patients with established chronic obstructive airways disease. Matched defects were found in all patients distributed throughout the lungs. Patients scanned during acute exacerbation frequently showed basal mismatched defects of ventilation (21 out of 30) and in a few follow-up scans showed resolution on treatment. Other patients also scanned in acute exacerbation showed unmatched defects of perfusion thought to represent pulmonary emboli. Poor correlation was found between scan defects assessed on a semiquantitative basis and conventional lung function tests.