COVID-19 Imaging Features

In March 2020, the third highest number of positive cases in the world was recorded in Italy, mainly due to 2 outbreaks of 2 different clusters in Lombardy and Veneto.

Fever is the most common symptom, followed by fatigue and dry cough; worsening of dyspnea and acute respiratory distress syndrome are found in severe cases. Previous reports have highlighted the key role of chest computed tomography (CT) and chest X-ray (CXR) in the diagnosis and follow-up of CoViD-19.

The most frequent clinical manifestation seems to be viral pneumonia, characterised by fever, cough, dyspnea. The severity of the disease varies widely: with evidence of mild disease in the majority of confirmed cases, severe pneumonia on a part of these, defined as dyspnea, hypoxia or lung involvement > 40% at imaging within 24-48 hours, and critical disease defined as respiratory failure, shock or multi-organ failure in particular patient cohorts.The mortality rate between cases ranges from approximately 4% in early reports to 14%, depending on the intensity of transmission and time of infection, and most fatal cases occurred in older patients or in patients with pre-existing medical co-morbidities.

Imaging plays an essential role in the diagnosis and follow-up of this infection.Several studies have been published describing the results of imaging, mainly using chest CT (computed tomography) with a limited number of articles describing disease in European patients or the possible different clinical/radiological presentation of the disease in European patients.

Pulmonary pathological findings appear to be similar to those previously described in SARS and MERS, with a prevalence of frosted glass densities and occasional consolidation.According to the literature, the 3 main features for the diagnosis of CoVid-19 pneumonia are: alveolar disease, represented by ground glass densities, bilateral distribution and prevalent peripheral involvement. This triad is more common in intermediate stages of the disease. In the early stages of the disease, a significant proportion of patients may present with negative or dubious X-rays and CT scans.There is an important overlap with imaging findings of other viral pneumonia, in particular with other members of the coronaviridae family: consolidation, however, seems to be less common in the early stages of CoViD-19 and bilateral distribution is less frequent in SARS and MERS pneumonia. Very little data have been published on the radiological evolution and modification of radiological aspects during infection: as the disease progresses, parenchymal consolidations begin to resorb and assume a frosted glass appearance. Another possible evolution is the progression towards the radiological aspect of the "white lung". This study aims to describe imaging aspects of CoViD-19 infection in Italian patients and the data on the radiological evolution.