Background: During the COVID-19 pandemic, there have been a number of waves of infections that have resulted in a number of variants of concern (VoC), with the majority of the identified variants being the Delta and Omicron variants. A chest CT scan plays an important role in the diagnosis, complications, and prognosis of COVID-19 patients. This systematic review aims to compare chest CT scan images between COVID-19 patients infected with the Delta and Omicron variants.
Methods: Study searches were conducted on three databases of electronic scientific journal publications, namely Google Scholar, PubMed, and Wiley Online Library. The study selection method used the PRISMA diagram with inclusion criteria are original study that examined a comparison of CT-scan images of the chest between COVID-19 patients with the Delta and Omicron variants. While the exclusion criteria set were studies in the form of commentaries, literature reviews, and meta-analyses, studies that were not available in Indonesian or English, and not available in full-text.
Results: The ten studies included in this systematic review consisted of 10 retrospective cohort studies that compared CT-scan images of the chests of COVID-19 patients with Delta and Omicron variants. Radiological features evaluated from the ten studies included ground glass opacity (GGO), consolidation, crazy paving pattern, vascular dilation, air bronchogram, bronchial wall thickening, bronchiectasis, presence of reticulation, subpleural lines, fibrosis, halo sign, reverse halo sign (Atoll sign), air bubble sign, and presence of pleural effusion. The majority of these radiological features were found to be higher in the Delta variant compared to the Omicron. Whereas for the classification of chest CT scan images based on RSNA, typical images were also found more in the Delta variant. The CT severity score, CO-RADS score, and COV-RADS score were also found to be higher in the Delta variant compared to Omicron.
Conclusion: In COVID-19 infection, the Delta variant showed a chest CT-scan showing typical COVID-19 pneumonia, whereas in the Omicron variant, more atypical features were found.