HRCT and pulmonary function tests in monitoring of lung involvement in juvenile systemic sclerosis

Abstract

To investigate the role of high-resolution computed tomography (HRCT) and pulmonary function tests (PFTs) in staging pulmonary involvement in juvenile systemic sclerosis (JSS). Clinical charts of 17 JSS patients (pts) were reviewed and high-resolution CT (HRCT) scans and PFTs performed at first and last visit were examined. Forced expiratory volume in 1 sec (FEV(1)), forced vital capacity (FVC) and carbon monoxide diffusing capacity [DL(CO)] were measured (% pred. values) while HRCT changes were graded according to the Schurawitzki method (min-max score: 0-18). At initial assessment, 10 pts (58.8%) had pulmonary involvement (HRCT score >0 and/or PFTs <80% pred. values). PTFs abnormalities were consistent with a restrictive defect, with low FEV(1), FVC and DL(CO) values and normal FEV(1)/FVC ratio. At first visit HRCT scores were inversely correlated with FEV(1) (r = -0.75; P = 0.02), FVC (r = -0.685; P = 0.035), and DL(CO) values (r = -0.71; P = 0.03), but not with the FEV(1)/FVC ratio (r = -0.36; P = 0.31). Stronger inverse correlations were detected at last visit (median time interval: 4.3 years; min-max: 1-10 years) between HRCT and FEV(1) (r = -0.86; P = 0.002), FVC (r = -0.79; P = 0.009) and DL(CO) (r = -0.79; P = 0.009), but not with the FEV(1)/FVC ratio (r = -0.33; P = 0.35). Changes in HRCT scores between first and last visit were correlated with changes in FEV(1) (r = -0.74; P = 0.02), FVC (r = -0.81; P = 0.007), but not in DL(CO) values (r = 0.07;P = 0.84). At the last visit, of the 10 pts with pulmonary involvement at initial assessment 5 showed worsening of lung involvement and 5 either no significant changes in PFTs and HRCT or mild improvement. PFTs, namely lung volumes, represent a reliable "monitoring" tool in children with JSS to identify pts that need to undergo an HRCT to rule out initial pulmonary involvement and to monitor the course of ILD over time. The weaker clinical value of DL(CO) may relate to poor lung function technique in some younger children.