Repeatability of lung density measurements with low-dose computed tomography in subjects with alpha-1-antitrypsin deficiency-associated emphysema

RATIONALE AND OBJECTIVES. Multislice computed tomography (MSCT) of the lung s provides a new opportunity for longitudinal assessment of lung densities because of shorter scan duration. The aim of the present study was to asses s the intraindividual variation of lung densities measured by MSCT of patie nts with emphysema. METHODS. Ten patients with emphysema participated in a study in which MSCT was obtained on two occasions, approximately 2 weeks apart. Scanning parame ters were 140 W, 20 mAs, 4 x 2.5-mm collimation, and effective slice thickn ess of 2.5 mm. Lung density was measured as the 15th percentile point and t he relative area below -910 Hounsfield units (HU) by using Pulmo-LKEB softw are. RESULTS. The mean difference of the 15th percentile point was -1.29 +/- 3.2 HU, and that for the relative area below the -910-HU parameter was -1.02% +/- 3.09%. Intraclass coefficients of variation were 0.96 (0.86-0.99) and 0 .94 (0.8-0.98), respectively (95% confidence interval). CONCLUSIONS. Lung density parameters of emphysema derived by MSCT provide a n opportunity for analysis of the treatment effects of new drugs on the pro gression of emphysema.