Chest CT for early detection and management of coronavirus disease (COVID-19): a report of 314 patients admitted to Emergency Department with suspected pneumonia

Abstract

Purpose: The purpose of our study was to assess the potential role of chest CT in the early detection of COVID-19 pneumonia and to explore its role in patient management in an adult Italian population admitted to the Emergency Department.

Methods: Three hundred and fourteen patients presented with clinically suspected COVID-19, from March 3 to 23, 2020, were evaluated with PaO2/FIO2 ratio from arterial blood gas, RT-PCR assay from nasopharyngeal swab sample and chest CT. Patients were classified as COVID-19 negative and COVID-19 positive according to RT-PCR results, considered as a reference. Images were independently evaluated by two radiologists blinded to the RT-PCR results and classified as "CT positive" or "CT negative" for COVID-19, according to CT findings.

Results: According to RT-PCR results, 152 patients were COVID-19 negative (48%) and 162 were COVID-19 positive (52%). We found substantial agreement between RT-PCR results and CT findings (p < 0.000001), as well as an almost perfect agreement between the two readers. Mixed GGO and consolidation pattern with peripheral and bilateral distribution, multifocal or diffuse abnormalities localized in both upper lung and lower lung, in association with interlobular septal thickening, bronchial wall thickening and air bronchogram, showed higher frequency in COVID-positive patients. We also found a significant correlation between CT findings and patient's oxygenation status expressed by PaO2/FIO2 ratio.

Conclusion: Chest CT has a useful role in the early detection and in patient management of COVID-19 pneumonia in a pandemic. It helps in identifying suspected patients, cutting off the route of transmission and avoiding further spread of infection.

Keywords: COVID-19; Chest CT; Emergency radiology; Pandemic; Pneumonia.

Fig. 1

Agreement and discrepancies between CT findings and RT-PCR: 147 COVID-19+ were CT positive; 128 COVID-19− were CT negative; 24 cases were CT positive with negative RT-PCR results; 15 cases were CT negative with positive RT-PCR results

Fig. 2

Percentage of COVID-19+ and COVID-19− for each radiological index

Fig. 3

A 75-year-old man presented with fever and dyspnea in the last 13 days, COVID+. a–b CT shows diffuse bilateral ground-glass opacities with prevalent peripheral distribution, septal thickening and small areas of consolidation with air bronchogram (mixed GGO and consolidation pattern)

Fig. 4

A 21-year-old man with dyspnea, cough and thoracic pain in the last two days, without fever and without history of COVID-19 exposure. CT shows a large area of consolidation with air bronchogram involving the lower lobe of the left lung suggesting bacterial lobar pneumonia. The patient, instead, was positive to the RT-PCR test

Fig. 5

Two cases of discrepancies between CT findings and RT-PCR results. a–b A 57-year-old man with diabetes and hypertension, admitted in critical condition for serious dyspnea and stupor. CT shows bilateral and mostly peripheral multifocal confluent areas of ground-glass opacity with a wide area of consolidation in the lower right lung (b). RT-PCR result was negative, and the final diagnosis was Klebsiella pneumoniae infection. c–d A 83-year-old man with cardiomyopathy and diabetes who presented with fever in the last 3 days and history of COVID-19 exposure. CT shows thin semilunar symmetric areas of peripheral subpleural increased density, bronchial wall thickness, signs of vascular congestion and cardiomegaly; these signs were interpreted as congested interstitial spaces and poorly aerated zones secondary to bronchitis and heart dysfunction. Instead, RT-PCR result was positive

Fig. 6

a–b CT scan in a 43-year-old man with fever and cough in the last 12 days shows the most typical and frequent features of COVID-19 pneumonia: bilateral multifocal and confluent ground-glass opacities in a peripheral subpleural distribution, associated with consolidation area in the left lower lobe. The patient was positive to RT-PCR test. c–d A 64-year-old man with cough and dyspnea for 10 days, treated at home with antibiotics without benefit and arrived to the hospital for the onset of fever in the last day. CT scan shows similar pattern and distribution of patient in figures a, b, but the first two swabs were negative. Anyhow, he was hospitalized and treated as a positive patient. The RT-PCR test turned positive only on the third sample