RecruitingDiagnostic testCT Quantitative Assessment of Interstitial Lung DiseaseInterstitial lung disease (ILD) refers to a broad category of heterogeneous lung diseases with different etiologies and features characterized by inflammation and fibrosis of the lung parenchyma and manifested as exertional dyspnea, interstitial patterns on high resolution computed tomography (HRCT), and abnormal pulmonary function tests (PFTs) The aim of this study is to investigate is there any correlation between changes seen in the lung parenchyma by HRCT and the pulmonary functions of the patients.