Computed Tomographic Imaging Features of COVID-19 Pneumonia Caused by the Delta (B.1.617.2) and Omicron (B.1.1.529) Variant in a German Nested Cohort Pilot Study Group

Abstract

Background: The aim of this study was to evaluate CT (computed tomography) imaging differences for the Delta and the Omicron variant in COVID-19 infection. Methods: The study population was derived from a retrospective study cohort investigating chest CT imaging patterns in vaccinated and nonvaccinated COVID-19 patients. CT imaging patterns of COVID-19 infection were evaluated by qualitative and semiquantitative scoring systems, as well as imaging pattern analysis. Results: A total of 60 patients (70.00% male, 62.53 ± 17.3 years, Delta: 43 patients, Omicron: 17 patients) were included. Qualitative scoring systems showed a significant correlation with virus variants; “typical appearance” and “very high” degrees of suspicion were detected more often in patients with Delta (RSNA: p = 0.003; CO-RADS: p = 0.002; COV-RADS: p = 0.001). Semiquantitative assessment of lung changes revealed a significant association with virus variants in univariate (Delta: 6.3 ± 3.5; Omicron: 3.12 ± 3.2; p = 0.002) and multivariate analysis. The vacuolar sign was significantly associated with the Delta variant (OR: 14.74, 95% CI: [2.32; 2094.7], p = 0.017). Conclusion: The Delta variant had significantly more extensive lung involvement and showed changes classified as “typical” more often than the Omicron variant, while the Omicron variant was more likely associated with CT findings such as “absence of pulmonary changes”. A significant correlation between the Delta variant and the vacuolar sign was observed.

Effect of vitamin D status on adult COVID-19 pneumonia induced by Delta variant: A longitudinal, real-world cohort study

“…The pneumonia lesion occurred at a median of 3 days after admission, peaked within 3 to 7 days after onset, and then began to be absorbed. Compared with the Omicron subvariant BA.2 previously studied in children (15), we found that the Delta variant had more extensive lung involvement and caused more extensive parenchymal changes on chest CT images, which was basically consistent with other emerging studies (5,18,19). However, CT images of pneumonia lesions in Delta and Omicron appear to be milder and less recognizable than those in WT and Alpha (17).…”

“…The application of clinical and CT imaging knowledge based on WT to guide the evaluation and treatment of Omicron variant-induced pneumonia may lead to certain bias. Furthermore, several recent cross-sectional studies have demonstrated that the Omicron variant shows fewer, less severe, and more "atypical" lesions on chest CT than the Delta variant (5,18,19). Despite differences and inconsistencies, Delta is still likely to be closest to Omicron in terms of timing of occurrence, vaccination status, and clinical and imaging features.…”

“…Till April 1, 2022, a total of 161 discharged adult patients infected with the Delta variant were included in this study, of which 101 (63%) were male and 46 (29%) presented with pneumonia. The median (IQR) age and baseline 25-hydroxyvitamin D concentration were 37 (28-47) years and 21 (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27) ng/ml, respectively. There were significant differences in age (34 vs. 43 years; p < 0.001), SARS-CoV-2 IgM titer (0.3 vs. 0.1 AU/ml; p = 0.002), SARS-CoV-2 IgG seropositive (84 vs. 44%; p < 0.001), and titer (82.8 vs. 3.3 AU/ml; p < 0.001), lymphocyte (1.36 vs. 0.87 × 10^9/L; p = 0.002) and platelet count (224 vs. 200 × 10^9/L; p = 0.04), fibrinogen (2.9 vs. 3.3 g/L; p < 0.001), and aspartate aminotransferase (27 vs.…”

Vaccination protects against acute respiratory distress syndrome (ARDS) in hospitalized patients with COVID-19

“…Tube current modulation CARE Dose4D at quality reference mAs of 100mAs and automatic tube voltage setting with CARE kV at 120kV reference with a collimation of 128x0.6mm was used. Depending on the clinical question that needed to be answered intravenous contrast agent was applied, as detailed elsewhere [11,12]. In cases with follow-up CT scans, only the rst acquired CT scan was evaluated.…”

Vaccination protects against mortality and intensive care unit (ICU) admission in hospitalized patients with COVID-19

“…Following the identi cation of the study cohort via the electronic hospital information system, pertinent clinical data were gathered from the electronic patient records. This data compilation included vaccination status, demographic particulars (age, sex), details of infection (including virus variant and symptom onset, COVID-19 antibodies), symptomatology (dyspnea, coughing, fever), pre-existing conditions (such as Body Mass Index (BMI) and pre-existing illnesses), laboratory parameters (C-reactive protein (CRP), procalcitonin (PCT), D-Dimer, PTT, INR, platelets, creatinine, urea, AST, ALT, pO2, pCO2), results of CT scans (quantitative score of chest CT lesions as detailed elsewhere (Askani et al, 2022(Askani et al, , 2023), speci cs of COVID-19 treatment (ICU admission, ICU duration, oxygen therapy), and any complications (sepsis, pulmonary superinfection, coagulopathy, pulmonary artery embolism, renal failure, mortality) that occurred.…”