Predictors of Pulmonary Hypertension on High-resolution Computed Tomography of the Chest in Systemic Sclerosis: A Retrospective Analysis

Abstract

Purpose To evaluate the imaging features on high-resolution computed tomography (HRCT) of the chest and the clinical parameters that are associated with pulmonary hypertension in systemic sclerosis. We specifically investigated whether main pulmonary artery (MPA) diameter and burden of lung fibrosis are predictors of pulmonary hypertension in these patients. Methods We retrospectively retrieved the database information of patients with systemic sclerosis seen at our hospital between January 2007 and December 2008. A total of 75 patients had HRCT of the chest, pulmonary function testing (PFT), and echocardiography within 6 months of each other. The echocardiography images were reviewed by a level-3 echocardiographer, and 29 cases were excluded because of suboptimal evaluation of pulmonary artery (PA) pressure. Peak PA pressures and PFT of the remaining 46 cases (43 women and 3 men) were charted. The PFT included total lung capacity (TLC), diffusion capacity of lung for carbon monooxide (DLCO) and the ratio of forced expiratory volume in one second and forced vital capacity (FEV1/FVC). The HRCT of the chest of each patient was read by a chest radiologist. The extent of ground glass, reticulation, and honeycombing was objectively scored. The maximum diameter of the main pulmonary artery (MPAD) and ascending aorta were measured. The ratio of main pulmonary artery diameter and ascending aortic diameter (MPAD/AD) and ratio of main pulmonary artery diameter and body surface area (MPAD/BSA) were also calculated. Results Statistical analysis done by using a multivariate model showed that the calculated fibrotic score strongly correlated with peak PA pressures ( P < .001). MPAD ( P = .0175), and the ratio MPAD/AD ( P = .0102) also showed a statistically significant correlation with peak PA pressures. By using stepwise regression analysis, the fibrotic score was found to be the most reliable independent predictor of pulmonary hypertension. Conclusion HRCT-determined severity and extent of pulmonary fibrosis may be helpful in screening for pulmonary hypertension in patients with systemic sclerosis.