Objectives: To assess the late phase CT changes of COVID-19 patients, and figure out factors predicting lung abnormality in late phase. Methods: : We conducted a retrospective study on 42 patients (14 males, 28 females;age 65±10 years) with COVID-19 admitted between February 7, 2020 and March 27, 2020. Only patients with at least 3 CT scans taken at least 3 weeks after initial symptom onset were included in the study. CT images were analyzed by 2 independent radiologists using different scoring: (1) area-based scoring (ABS);and (2) intensity-weighted scoring (IWS). Temporal changes in the average lung lesion were evaluated by averaged area under the curve (AUC) of the CT score-time curve. Correlations between averaged AUCs and clinical characteristics were determined. Results: Temporal changes in lung abnormalities during recovery (weeks 3 through 8) of CT findings using the ABS system were variable (P=0.934). By contrast, the IWS system detected more subtle changes in lung abnormalities during the late phase of recovery in COVID-19 patients, with consistent week-to-week relative reductions in IWS (P=0.025). In assessing the correlation between averaged AUCs and clinical characteristics, strong relationships were observed with D-dimer and C-reactive protein (CRP) levels on admission, with hazard ratios (HR)(95%CI) of 5.32 (1.25-22.6)(P=0.026) and 1.05 (1.10-1.09)(P=0.017), respectively. Conclusion: Our results suggest an intensity-weighted rather than area-based scoring system is more sensitive to detect subtle temporal CT changes in COVID-19, with D-dimer and CRP levels on admission being predictive of the time course of late phase recovery from the disease.
Computation Tomography (CT)-Based Evaluation of Temporal Changes in Lung Abnormalities During the Recovery Stage in COVID-19 In-Hospital Patients