Imaging patterns found on pulmonary CT scans of COVID-19 patients may vary depending on which variant of concern (VOC) has infected the patient according to new research presented Wednesday morning.
Yüksel
"The typical CT findings in COVID-19 patients are well-understood," said Can Yüksel, MD, a radiology resident at the University Hospital RWTH in Aachen, Germany. "However, CT morphology associated with the Delta VOC may diverge from the predominant COVID variants."
COVID-19 pneumonia has been described as bilateral, multifocal ground glass opacifications (GGOs), and consolidations with peripheral emphasis and interlobular septal thickening.
Differences in Imaging for Variants
To determine whether the Delta variant may be associated with a different imaging phenotype, Dr. Yüksel's team assessed 161 CT studies of patients confirmed with SARS-Covid-2 infection with a positive PCR test result within two days of the CT exam. The CT scans were performed between January and September of 2021 at University Hospital RWTH.
After exclusions, 86 CTs of unique patients were analyzed, including 25 with a non-VOC, 22 with the Delta VOC, and 39 with the Alpha VOC.
"Patients with the Delta variant were significantly younger than patients in the Alpha and non-VOC cohorts," Dr. Yüksel said.
The average age of the Delta cohort was 49.1 years old; in the Alpha group it was 60.8, and in the non-VOC cohort it was 68. The vaccination rate for the entire cohort was 11.6% with a similar number of vaccinated patients in each subgroup.
The CT scans were analyzed for the distribution, configuration, and degree of involvement of GGOs and consolidations, the mean density and multifocality of lesions, and other CT morphological signs known to be associated with atypical pneumonia.
The researchers found no congruence between vaccination status and the presence of pathological lung alterations. Observed differences between the variants included:
- Consolidations with basal emphasis were more often seen in Alpha versus non-VOC
- Consolidations were less often centrally emphasized in Delta versus non-VOC
- GGOs and multifocal lesions were less likely to appear in Delta patients.
Most significantly, Dr. Yüksel said round pulmonary masses with a surrounding ground-glass halo were observed in three Delta patients but in none of the patients with the Alpha or non-VOC variants.
"This pattern is typically found in fungal infections and has not been established as a notable imaging pattern in COVID-19 pneumonia," he said.
The patients were all under 30 years old and otherwise healthy. None were suspected of a pulmonary co-infection.
"These findings may indicate that CT morphology is altered based on the virus variant," he said. "Radiologists may face additional phenotypes for COVID-19, especially if the Omicron and future variants lead to further changes."
Access the presentation, "Possible Alterations of Imaging Patterns in Computed Tomography for Delta-VOC of SARS-CoV-2," (W1-STCE-1) on demand at Meeting.RSNA.org.
