Objectives: To elucidate the chest HRCT imaging manifestations in coronavirus (COVID-19) infected Indian patients, study and compare the patterns identified during time course and among differently aged patients.

Materials and Methods: A retrospective observational study of 500 laboratory-confirmed SARS-CoV-2 infected patients was performed. The patients were categorized into 3 groups based on the time interval between onset of symptom and HRCT imaging and according to their age. The distribution, patterns, and extent of lung abnormalities were recorded.

Results: A predominant peripheral distribution of the abnormalities was observed as in 262/390 patients (67.2%). The Mean CT score of the right lower lobe (2.06 ± 1.13) and left lower lobe (2.01 ± 1.128) were significantly greater than other lung lobes (P-value < 0.001). Overall, most commonly observed pattern on imaging was crazy-paving pattern observed in 329/390 patients (84.4%). In the early phase of the disease (0-7 days), predominant patterns were crazy-paving (90.7%) and GGO with consolidation (50.4%). The consolidation pattern and the vacuolar sign showed a significant rise during advanced phase of the disease (8-14 days of symptom onset) and eventually decreased during the absorption phase (> 14 days after symptom onset). The reticular pattern, subpleural line sign were the dominant patterns observed during the absorption phase. The Mean total CT severity score (9.79 ± 4.79) was greatest for group C patients: age ≥ 45 years. (P-value < 0.001). GGO with consolidations was more common in group B (25-44 years) and C, whereas GGO plus reticulations and reticular pattern were more common in group C (P-value < 0.001).

Conclusion: HRCT features of COVID-19 pneumonia vary according to the disease course and the patient’s age. Crazy-paving pattern is dominant during the early phase and repairing signs during the absorption phase. The extent and pattern of involvement are more severe in the elderly population.