Abstract
Introduction: Quantitative computed tomography (CT) densitometry using the percentile density method may provide a sensitive assessment of lung structure for monitoring parenchymal damage. We aimed to evaluate the optimal percentile density score in SSc by quantitative CT densitometry, against pulmonary function.
Methods: We investigated 41 SSc patients by chest CT scan and lung function tests. Lung volumes and the nth percentile density (between 1 and 99%) of the entire lungs were calculated from CT histograms. The nth percentile density is defined as the threshold value of densities expressed in Hounsfield units. A prerequisite for an optimal percentage was its correlation with baseline DLCO%predicted. We performed progression analysis on CT scans from 2 patients with distinct lung function changes.
Results: Regression analysis for the relation between DLCO%predicted and the nth percentile density was optimal at 85% (Perc85). There was significant agreement between Perc85 and DLCO%predicted (R=-0.49, P=0.001) and FVC%predicted (R=-0.64, P<0.001). Two patients showed a marked change in Perc85 over a two year period.
Conclusions: We identified Perc85 as optimal lung density parameter, which correlated significantly with DLCO and FVC, confirming a lung parenchymal structure-function relation in SSc. This provides support for future studies to determine whether structural changes do precede lung function decline.
- Copyright ©ERS 2015
