Quantitative Tomographic Analysis as a Prognostic Tool in Connective Tissue Disease-Associated Interstitial Lung...

Background/Objectives: Interstitial lung disease (ILD) is the main thoracic manifestation of connective tissue diseases (CTDs) and is associated with high morbidity and mortality. High-resolution computed tomography (HRCT) of the chest is considered the gold standard imaging method for detecting and accurately characterizing ILD. This study aims to perform longitudinal visual and quantitative analyses of HRCT scans of patients with ILD secondary to CTD (ILD-CTD) and to correlate these findings with clinical outcomes (functional decline and death) in order to identify tomographic prognostic markers. Methods: This retrospective and longitudinal study included 195 patients with CTD who underwent HRCT at baseline and after two follow-ups. Data collected included initial disease extent and subjective impression of progression, as well as quantitative parameters such as lung volume and mean lung density. Forced vital capacity (FVC) and diffusion capacity of carbon monoxide (DLCO) values were also recorded, along with information on patient outcome. Results: Quantitative and visual assessments demonstrated moderate agreement in estimating ILD extent. Variations in lung volume, ground-glass index, pulmonary vascular volume-to-lung volume ratio, and disease extent correlated with subjective perception of disease progression. Lung volume reduction and increased disease extent were associated with FVC decrease at follow-up 1, whereas an increased fibrosis index correlated with reduced FVC at follow-up 2. No quantitative parameter was associated with mortality risk. Conclusions: The results support the potential benefit of using quantitative CT analysis as a complementary tool to pulmonary function tests and visual analysis in the longitudinal evaluation of ILD-CTD.