Use of Quantitative CT Analysis to Evaluate the Degree of Lung Destruction in Lymphangioleiomyomatosis

Abstract

Background: Lymphangioleiomyomatosis (LAM) is a multisystem disease that mainly presents with cystic damage in the lungs. The purpose of this study was to quantify the degree of pulmonary cystic damage in CT and to compare its correlation with pulmonary function tests (PFTs) and serum levels of vascular endothelial growth factor (VEGF-D). Subjects and methods: 21 patients were included and 36 CT scans and PFTs were analyzed. The correlation of serum VEGF-D levels of 17 patients and their 24 CT scans were studied. Cystic areas were identified by the software. The volumetric percentage of cystic regions of the total lung volume was calculated to get a cyst score. A ROC curve was calculated to select the threshold at which the cyst scores could predict the lung impairment best.Results: The cyst scores correlated best with FEV1%pred (r = -0.72, p<0.01) and DLCO%pred (r = -0.82, p<0.01). The correlation with serum VEGF-D levels (r = -0.143, p = 0.506) was not obvious. The Youden Index is max (0.667) when cyst score is 15.80%. Conclusion: The pulmonary cyst scores on CT is strongly correlated with FEV1%pred and DLCO%pred. However, the association with serum levels of VEGF-D is not obvious. Cyst score >15.80% might indicate an abnormal lung function and patients are recommended a sirolimus treatment.