Pulmonary alveolar proteinosis: quantitative CT and pulmonary functional correlations

We assessed the relationship between quantitative computer tomography (qCT) and the pulmonary function test (PFT) or blood gas analysis in pulmonary alveolar proteinosis (PAP) patients, as well as the utility of these analyses to monitor responses to whole lung lavage (WLL) therapy.

Thirty-eight PAP patients simultaneously received a CT scan and PFT. Fifteen of these patients, undergoing sequential WLL for a total of 20 lavages, also underwent chest CT scans and blood gas analysis before and after WLL, and 14 of 15 patients underwent simultaneous PFT analysis. Differences between the qCT and PFT results were analyzed by canonical correlation.

PAP patients with low predicted values for FVC, FEV1, D(LCO) and D(LCO)/VA indicated small airspace volume and mean lung inflation, low airspace volume/total lung volume ratio and high mean lung density. Correlation and regression analysis revealed a strong correlation between D(LCO) and PaO(2) values with CT results. The qCT results indicated that WLL significantly decreased lung weights and mean lung densities, and improved the total airspace volume/total lung volume ratios and mean lung inflations.

Quantitative CT may be a sensitive tool for measuring the response of PAP patients to medical interventions such as WLL.