Chest CT images analysis
Three radiologists (18 years thoracic radiology specialist, 10 years general radiologist and 2 years radiologist resident) blinded to RT-PCR results reviewed CT images and concluded either to COVID-19 infection or not, according to the consensual signs described in COVID-19 chest damages7. Clinical history was available for interpretation.
Chest CT signs were analysed according to the Fleishner Society glossary18 : ground glass-opacities (patchy, nodular or mixed), crazy paving (thickened intralobular and interlobular lines in a ground glass opacity), subpleural curvilinear bands, consolidation areas, air bubble sign, vascular dilatation, bronchial distortion, reticular interlobular thickening, pleural effusion, pleural thickening, number of involved lobes, inferior predominance, laterality, lung localisation (subpleural, central or dual distribution), compatible CT aspect of ARDS) compatible CT aspect of organized pneumonia, compatible CT aspect of cardiac failure, lymphadenopathy, emphysematous lesions, bronchial thickening, endobronchial secretion, centrilobular nodule, and total lung volume involvement (0%, < 10%, 10-25%, 25-50%, 50-75%, > 75 %).
Compatible CT aspect of organized pneumonia included consolidation (nodular, linear, perilobular, or peribronchovascular), subpleural curvilinear bands, halo sign, and/or atoll sign.19Bronchial distortion is defined as bronchial dilatation, with irregular contours, focalized in the areas affected by the ground glass opacities, consolidation, or crazy paving.20