A collaborative team from the Icahn School of Medicine at Mount Sinai in New York and hospitals affiliated with Nanchang, Qingdao, and Sun Yat-sen Universities in China, set out to characterize the key chest CT imaging findings in a group of patients infected with the novel coronavirus (2019-nCoV). Their goal was to familiarize radiologists and clinical teams with the imaging manifestations of this new outbreak.
The retrospective case series is published in Radiology in the article “CT Imaging Features of 2019 Novel Coronavirus (2019-nCoV).” In the report, the team presented a review of chest CT scans of 21 symptomatic patients from China infected with 2019-nCoV—with a focus on the identification and characterization of the most common findings. The team’s hope is that describing these CT imaging features could aid in the early detection and diagnosis of Wuhan coronavirus.
“Early disease recognition is important not only for prompt implementation of treatment, but also for patient isolation and effective public health surveillance, containment, and response,” said Michael Chung, MD, assistant professor in the department of diagnostic, interventional and molecular radiology at Icahn School of Medicine at Mount Sinai.
The respiratory illness that emerged from Wuhan, China at the end of 2019 resembles viral pneumonia clinically—manifesting as fever, cough, and shortness of breath. There are over 37,000 confirmed cases of the novel coronavirus and at least 813 deaths.
From January 18 to January 27, 21 patients admitted to three hospitals in three provinces in China with confirmed 2019-nCoV infection underwent chest CT scans. The 21 patients consisted of 13 men and 8 women ranging in age from 29 to 77 years old, with a mean age of 51.2 years. All patients were confirmed positive for infection via laboratory testing of respiratory secretions.
For each of the 21 patients, the initial CT scan was evaluated for the following characteristics: (1) presence of ground-glass opacities, (2) presence of consolidation, (3) number of lobes affected by ground-glass or consolidative opacities, (4) degree of lobe involvement in addition to overall lung “total severity score,” (5) presence of nodules, (6) presence of a pleural effusion, (7) presence of thoracic lymphadenopathy (lymph nodes of abnormal size or morphology), and (8) presence of underlying lung disease such as emphysema or fibrosis. Any other thoracic abnormalities were also noted.
The analysis showed that 2019-nCoV typically manifests on CT with bilateral ground-glass and consolidative pulmonary opacities. Nodular opacities, crazy-paving pattern, and a peripheral distribution of disease may be additional features helpful in early diagnosis. The researchers also noted that lung cavitation, discrete pulmonary nodules, pleural effusions, and lymphadenopathy are characteristically absent in cases of 2019-nCoV.
Follow-up imaging in seven of eight patients showed mild or moderate progression of disease as manifested by increasing extent and density of airspace opacities.
Chung cautioned that absence of abnormal CT findings upon initial examination does not rule out the presence of 2019-nCoV.
“Our patient population is unique from other published series on the Wuhan coronavirus in that three of our patients had normal initial chest CTs,” he said. “One of these patients progressed three days later and developed a solitary nodular ground-glass lesion in the right lower lobe, indicating this pattern may represent the very first radiologically visible manifestation of disease in some patients infected with Wuhan coronavirus.” Chung added that a second patient had a normal follow-up chest CT four days after her initial normal imaging exam.
“This suggests that chest CT lacks complete sensitivity and does not have a perfect negative predictive value,” Chung said. “We can’t rely on CT alone to fully exclude presence of the virus.”
This finding may be related to the observation that infection with 2019-nCoV is characterized by an incubation period of several days, and there may be a phase where viral infection manifests with symptoms prior to visible abnormalities on CT.
The researchers noted that further study is required to understand how patients fare after treatment but suggest that experience and imaging findings from MERS and SARS epidemics might be helpful in managing the current outbreak.