Lymphangioleiomyomatosis: Correlation of qualitative and quantitative thin-section CT with pulmonary function tests and assessment of dependence on pleurodesis

PURPOSE: To explore the relationship between findings at thin-section computed tomography (CT) and pulmonary function tests in lymphangioleiomyomatosis (LAM) and to evaluate the influence of pleurodesis on this relation and the effectiveness of quantitative versus qualitative CT in the assessment of disease severity. MATERIALS AND METHODS: Thirty-seven patients with LAM (17 with pleurodesis) underwent CT and pulmonary function tests. The severity of pulmonary cystic involvement was graded qualitatively by two independent readers and measured quantitatively at CT with a thresholding technique. Relationships between findings at CT and pulmonary function tests and the influence of pleurodesis on these findings were assessed with regression analysis and analysis of covariance. RESULTS: Qualitative ratings had good agreement between observers (kappa = 0.75). Quantitative CT had good repeatability and showed significant correlation with the percent predicted forced expiratory volume in 1 second (FEV1%) (r = 0.67, P < .001), percent predicted diffusing capacity of lung for carbon monoxide (DLCO%) (r = 0.48, P < .005), percent predicted ratio of residual volume to total lung capacity (RV/TLC%) (r = -0.65, P < .001), and percent predicted TLC (r = 0.34, P < .04). Quantitative CT results were somewhat better than qualitative CT results. The standard error of the FEV1% for the quantitative CT was about 85% of that for the qualitative CT. Pleurodesis had no statistically significant effect on the slope of the regression line between quantitative CT findings, FEV1%, and DLCO% (corrected for alveolar volume). The slope between quantitative CT and RV/TLC% was significantly (P = .044) more negative in patients with pleurodesis. CONCLUSION: Qualitative and quantitative CT findings correlate with pulmonary dysfunction over a wide range of disease severity in patients with LAM. Pleurodesis influences the relationship between CT measurements and pulmonary function test results. (C) RSNA, 2002.