Quantitative CT indexes are significantly associated with exercise oxygen desaturation in interstitial lung disease related to systemic sclerosis

Introduction: Interstitial Lung Disease (ILD) is the first cause of death related to Systemic Sclerosis (SSc). The ILD severity can be assessed with clinical, functional and radiological outcome. Nevertheless none of them is completely validated in clinical practice. Recently a new radiological evaluation based on Quantitative Computed Tomography Indexes (QCTI) was proposed on the basis of voxel-wise quantitative analysis of chest CT. Objectives: The main aim of this study is to verify if QCTI can identify SSc patients with significant oxygen desaturation during the 6 min walking test. The discrimination performance of QCTI and the other clinical, functional and radiological outcomes was also investigated. Methods: Sixty three SSc patients were enrolled and underwent clinical, functional and radiological assessment. Inspiratory chest CT of each patient was evaluated with both a visual score and a dedicated software for segmentation of the lung in order to obtained QCTI. Results: Patients with or without severe oxygen desaturation showed different QCTI, CT visual score and functional outcomes (P<0.05). In particular, QCTI and functional outcomes showed almost the same discriminating ability. Conclusion: QCTI detect SSc patients with a severe oxygen desaturation after exercise as well as functional and other radiological outcomes. It is remarkable that QCTI are the only outcome without intra- or inter-reader variability because they are obtained with an algorithm. These findings bring out the QCTI as a concrete tool in SSc-ILD assessment.