Systemic sclerosis interstitial lung disease evaluation: comparison between semiquantitative and quantitative computed tomography assessments

The pulmonary fibrosis extent in systemic sclerosis (SSc) has a prognostic value. Chest Computed Tomography (CT) is the gold standard to detect an interstitial lung disease (ILD). Semi-quantitative scores and quantitative methods can estimate the ILD. The first ones have a considerable inter-intraobserver variability, while quantitative scores, based on distribution of lung attenuation parameters (also called CT indexes), can be obtained through expensive and not so user-friendly software. The aim of this work is to investigate whether a DICOM-viewer open-source software (OsiriX) can obtain CT indexes correlating with semi-quantitative scores. Sixty-three chest CTs of ILD-SSc patients were assessed with two semi-quantitative methods (visual extent and limited/extensive ILD grading) and then blindly processed with OsiriX to obtain the distribution parameters of lung attenuation (kurtosis, skewness and mean). Semiquantitative assessment and CT indexes were compared through the Spearman rank test and Mann-Whitney test. All CT indexes showed a statistically significant correlation of moderate degree with the visual extent semi-quantitative assessment (p-value less than 0.05). Skewness was the lung attenuation distribution parameter with the strongest correlation (r =-0.378, p-value = 0.0023). Moreover, CT indexes of patients with an extensive and limited disease were statistically different (p less than 0.01). CT indexes correlating with a radiological semi-quantitative ILD assessment can be obtained through OsiriX. CT indexes can be considered very helpful to discriminate patients with extensive and limited ILD.