Chest CT imaging features of COVID-19 pneumonia: First radiological insights from Porto, Portugal

Introduction: The outbreak of a highly infectious respiratory disease – COVID-19 - has spread globally and a novel type of coronavirus (SARS-CoV-2) was identified as its cause. Chest CT findings have been described as an aid for COVID-19 diagnosis and management. We aimed to describe the CT imaging characteristics in a group of COVID-19 patients while we also intended to assess if any of these radiological features were associated with short-term prognosis. Materials and methods: CT examinations from 164 consecutive patients with at least one positive RT-PCR nucleic acid assay for SARS-CoV-2 were retrospectively analyzed. Numerous CT imaging features were recorded independently by two radiologists. Patients were grouped according to their status 14 days after the initial CT scan in either discharged/hospitalized in a non-ICU ward (favorable prognosis group) versus deceased/admitted to an intensive care unit (unfavorable prognosis group). Results: Ground-glass opacities (89.0 %) and consolidations (73.2 %) with multilobar involvement were the predominant imaging findings, while a nodular pattern (3.7 %) and cavitation (1.2 %) were uncommon. Mean age was higher in the mortality/ICU group. Ground-glass opacities and consolidations were dominant in both groups, but distribution pattern of abnormalities was different, being more often diffuse in the mortality/ICU group. Linear opacities and opacities that were rounded in shape were more frequently observed in the favorable prognosis group. CT severity index was significantly higher in the mortality/ICU group. For assessing unfavorable prognosis, the best cut-off for CT severity index was 24 (sensitivity 78 %; specificity 59 %). Interobserver agreement for all CT findings was excellent. Conclusion: COVID-19 pneumonia in Porto, Portugal, manifests as multilobar ground-glass opacities and consolidations. Older age, diffuse distribution and increasing CT severity index are associated with worse short-term prognosis while linear opacities resembling organizing pneumonia and rounded opacities herald a more favorable prognosis.