Comparison of CT Features of Omicron and Influenza A-H1N1-Associated Viral Pneumonia:Initial Onset and Follow-Up / 中国医学影像学杂志

ABSTRACT

Purpose To compare the CT imaging features of the novel coronavirus Omicron variant and influenza A-H1N1-associated viral pneumonia,and to investigate the factors associated with the uptake process of the two pneumonias.Materials and Methods A total of 43 patients with Omicron virus pneumonia(Omicron group)and 30 patients with influenza A(H1N1)virus pneumonia[influenza A(H1N1)group]in Civil Aviation General Hospital from December 2022 to March 2023 were retrospectively collected.The clinical data of the two groups were compared,including age,gender,symptoms(fever or not),duration of symptoms and incidence of complications.White blood cells,monocytes,lymphocytes,neutrophils,C-reactive protein,etc.]and initial and follow-up CT imaging features[lesion density,distribution,signs and qualitative CT severity score(CTSS)].Results The mean age of patients in Omicron group was higher versus that in H1N1 group[(68.61±15.94)years vs.(51.20±16.39)years,P<0.000 1],and the fever rate in Omicron group(58.1%vs.86.7%,P=0.009)and monocyte count[(0.40±0.16)vs.(0.58±0.19),P<0.000 1]were lower than those in the influenza A(H1N1)group.Chest CT showed that the lesions of patients in the Omicron group were mainly distributed under the pleura,and the lesions of patients in the influenza A(H1N1)group were mainly distributed under the pleura and along the bronchovascular bundle(χ2=8.592,P=0.035).Patients in the Omicron group were more likely to have interlobular septal thickening(χ2=11.753,P=0.001),paving pattern(χ2=16.216,P<0.000 1),air bronchogram(χ2=16.216,P<0.000 1),pleural effusion(P=0.039)and pleural thickening(χ2=4.067,P=0.044)than patients in the influenza A(H1N1)group,while patients in the influenza A(H1N1)group were more likely to have nodules than those in the omicron group(χ2=6.971,P=0.008).The CTSS scores of patients in the omicron group were higher than those in the influenza A(H1N1)group at the initial diagnosis(Z=413,P=0.009)and follow-up(Z=107,P=0.027).The correlation between the change of follow-up CTSS and the initial CTSS in the Omicron group was the strongest(r=0.689,P<0.000 1).There was the strongest correlation between the change of follow-up CTSS and the duration of symptoms in influenza A(H1N1)group(r=0.954,P<0.000 1).Conclusion Patients in the Omicron group have a higher range of initial and follow-up lesions than those in influenza A(H1N1)group,and the degree of pneumonia absorption in the omicron group may be related to the initial CTSS,whereas in the influenza A(H1N1)group it may be related to the duration of symptoms.