Clearance of inhaled 99mTc-DTPA predicts the clinical course of fibrosing alveolitis.

The aim of this study was to determine whether the speed of technetium-labelled diethylene-triamine-pentacetate (99mTc-DTPA) clearance from the lung is predictive of disease progression in fibrosing alveolitis, as judged by changes in respiratory function tests. 82 nonsmoking patients with fibrosing alveolitis were studied (progressive systemic sclerosis, n = 53; lone cryptogenic fibrosing alveolitis, n = 29). Normal 99mTc-DTPA clearance at initial measurement predicted stable disease; rapid 99mTc-DTPA clearance identified patients at risk of deterioration. Repeat measurement of clearance, approximately 12 months later, enabled the definition of a subgroup at higher risk, with persistently abnormal 99mTc-DTPA clearance, and a smaller subgroup in whom reversion of clearance to normal was associated with a sustained improvement in respiratory function indices. These findings were not attributable to differences in treatment between subgroups. We conclude that the speed of 99mTc-DTPA clearance discriminates between stable and progressive disease in fibrosing alveolitis.