The sup(99m)Tc-DTPA static ventilation scan: Pathophysiological correlates of scintigraphic patterns

Small particle (<= 2 μm) sup(99m)Tc-DTPA radioaerosol can be easily and cheaply produced with a commercial nebulizer, well suited for the evaluation of small and large airway patency, as reflected by MEF75 and FEV1 respectively, with a diagnostic yield comparable to non hydrosoluble radioaerosols. sup(99m)Tc-DTPA allows the distinctive advantage of measuring also pulmonary alveolar capillary permeability in the same study. The implementation of quantitative descriptions of the scan by the 'penetration index' proposed for non hydrosoluble radioaerosols although possible is frought with reproducibility problems, the correlation of such index with the pulmonary function tests is poor. Semiquantitative descriptions of the deposition patterns are preferable. An original method proposed and validated in this study is quite easy to implement and it yields a high correlation with pulmonary function tests. The sensitivity of sup(99m)Tc-DTPA for the diagnosis of bronchial obstruction is very high and superior to routine pulmonary function tests. In addition the ventilation scan allows the topographical localization of the obstruction(s). (orig.)