Radiologist experts say CT alone not enough to rule out the presence of coronavirus

A team of expert radiologist researchers say that computed tomography imaging alone is not enough to exclude the presence of novel coronavirus in patients.

That’s one of the key takeaways from a new special report, published Tuesday in the journal Radiology. Scientists from Mount Sinai Health System and other institutions noted that in multiple cases, the absence of abnormal CT findings wasn't adequate to rule out the presence of 2019-nCoV. For instance, one patient in the study had a normal follow-up chest scan four days after her initial examination, which also showed no regularities.

“This suggests that chest CT lacks complete sensitivity and does not have a perfect negative predictive value,” lead author Michael Chung, MD, assistant professor in the Department of Diagnostic, Interventional and Molecular Radiology at the New York City institution, said in a statement. “We can’t rely on CT alone to fully exclude presence of the virus.”

The novel coronavirus outbreak has escalated quickly over the last few weeks, killing 427 individuals and sickening 20,000 more across the globe. Spotting it early on can prove crucial, the team noted, requiring radiologists to stay on their toes when presented with its symptoms.

Based on their review of cases tied to 21 patients, admitted to three Chinese hospitals last month, the team noted that coronavirus typically manifests on CT with bilateral ground-glass and consolidative pulmonary opacities. Nodular opacities, crazy-paving pattern, and a peripheral distribution of disease are additional features that may be helpful in early diagnosis, they added. Meanwhile, lung cavitation, discrete pulmonary nodules and pleural effusions are commonly absent in CT scans.

Follow-up imaging demonstrated mild or moderate progression of the disease in seven of eight patients. Chung noted that the study population is unique from previous case studies in that three individuals had normal initial chest CTs, and one progressed three days later, developing a solitary nodular ground-glass lesion in the right lower lobe.  

“This pattern may represent the very first radiologically visible manifestation of disease in some patients infected with Wuhan coronavirus,” Chung said.

The lack of sensitivity in CT may be because coronavirus has an incubation period of several days, and there could be a phase where viral infection manifests with symptoms before abnormalities pop up on CT, the team wrote. Further studies are needed to determine how individuals respond to treatment, but for now, Chung et al. urged radiologists to look to experience from the MERS and SARS epidemics in managing this new condition.