Multimodality imaging of COVID-19 pneumonia: from diagnosis to follow-up. A comprehensive review

•The awareness of imaging findings of COVID-19 pneumonia and their relationship with pathogenesis is useful in providing a confident diagnosis.•Chest X-ray might be used as first-line imaging modality in the areas with high prevalence of disease.•HRCT plays a pivotal role in the assessment of complications and differential diagnosis with other infectious and non- infectious lung disease. Due to its pandemic diffusion, SARS- CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) infection represents a global threat. Despite a multiorgan involvement has been described, pneumonia is the most common manifestation of COVID-19 (Coronavirus disease 2019) and it is associated with a high morbidity and a considerable mortality. Especially in the areas with high disease burden, chest imaging plays a crucial role to speed up the diagnostic process and to aid the patient management. The purpose of this comprehensive review is to understand the diagnostic capabilities and limitations of chest X-ray (CXR) and high-resolution computed tomography (HRCT) in defining the common imaging features of COVID-19 pneumonia and correlating them with the underlying pathogenic mechanisms. The evolution of lung abnormalities over time, the uncommon findings, the possible complications, and the main differential diagnosis occurring in the pandemic phase of SARS-CoV-2 infection are also discussed.