Findings captured during emergency scans intended to pinpoint stroke can reveal viral infection.
CT scans conducted in the emergency department on patients suspected of having a stroke may also identify individuals who are infected with SARS-CoV-2, the virus that causes COVID-19.
Based on the examination of patients from three London Hyper-Acute Stroke Units, a team of researchers from King’s College London determined carotid CTA scans of the head and neck blood vessels can accurately reveal patients who should subsequently be tested for the virus.
The team published their results in the Sept. 17 American Journal of Neuroradiology.
“Early identification of patients with COVID-19 is essential for treatment and viral control,” said the team led by Tom Booth, Ph.D., senior lecturer in neuroimaging at Kings College. “Therefore, the search for alternative diagnostic biomarkers for COVID-19 is mandated in the context of asymptomatic and pre-symptomatic infection and the variable sensitivity of SARS-CoV-2 RT-PCR testing.”
At the time the CTA scans were conducted, the team pointed out, only 15 percent of RT-PCR results were complete. The slow rate of return underscores the need for reliable alternative diagnostic COVID-19 biomarkers.
By analyzing scans from 225 patients who were initially examined for possible stroke, the team noticed ground glass opacities (GGO) in the tops of the lungs caught on the emergency images in 22.2 percent of patients. Compared with RT-PRC results, the diagnostic performance was strong – 75 percent sensitivity and 81 percent specificity. The team also determined that GGO at the top of the lungs was an independent predictor of increased 30-day mortality.
The team referred to GGO identified on a CTA scan as “free information” since it can be gleaned from an image intended for a different diagnostic purpose.
These results expand the type of exams radiologists can use to identify more patients who are positive for COVID-19 but who do not present to the hospital with characteristic symptoms of the virus as their major complaint. A recent study published in Abdominal Radiology detailed that evidence of COVID-19 infection can also be found in the bottom of the lungs captured in abdominal CT scans.
Alongside identifying the patients who will need additional medical services, the team said, these findings can be used to help staff prevent avoidable exposures.
“The implications of our findings plausibly include earlier selection of the appropriate level of personal protective equipment and attendant staff numbers, triage to appropriate inpatient ward settings, self-isolation, and contact tracing,” the team explained. “Biomarkers, such as a scan positive for GGO, should heighten awareness of a potential positive case, possibly changing staff personal protective equipment requirements and also directing a patient to a side room instead of an open ward, pending RT-PCR results.”