Temporal changes of lung computed tomography findings pulmonary COVID-19 infection.

OBJECTIVES: COVID-19 infection demonstrates characteristic findings in chest CT. The optimal timing of repeated CT scans still needs to be clarified, and the optimal time to assess imaging clearance in COVID-19 is still unknown. It is crucial to have a roadmap of the imaging course of COVID-19 pneumonia to develop guidelines for prompt diagnosis of pulmonary complications, especially fibrosis, at the earliest stage. PURPOSE: To assess the temporal changes of chest CT findings in patients with COVID-19 pneumonia and evaluate the rate of a complete resolution and determine the patients are at excessive risk for residual parenchymal abnormalities. MATERIALS AND METHODS: This retrospective observational study included 48 patients with real-time polymerase chain reaction-confirmed COVID-19 who were admitted to three academic hospitals. These patients underwent at least one initial chest CT before or after admission and at least one follow-up CT scan four weeks or more after the onset of the symptoms. All chest CTs were categorized according to time of performance into four groups, including the first week, second week, third-fourth week, and more than 28 days. Lung involvement was categorized as predominantly alveolar (ground-glass opacity and consolidation), organizing pneumonia, and reticular patterns. The severity of involvement was also evaluated by the reader. RESULTS: Forty-eight patients and a total of 130 chest CT scans were evaluated. The alveolar pattern showed a gradual decrease in frequency from 91% in the first week to 9% after the fourth week of the disease but the organizing pneumonia pattern gradually increased with disease progression and the frequency of reticular pattern increased significantly after third week. Complete resolution of CT findings was seen in 17 patients (13.1%) and was significantly more prevalent in patients of younger age (p value<0.001) and with lower initial CT severity scores (p value=0.048). CT severity scores in the second week were significantly higher in ICU admitted patients (p value=0.003). CONCLUSION: There are temporal patterns of lung abnormalities in patients with COVID-19 pneumonia. The predominant CT pattern was alveolar infiltrate in the first and second weeks of the disease, replaced with an organizing pneumonia pattern in the third and fourth weeks. Progression of lung involvement was correlated with ICU admission due to the highest CT severity score in the second and third weeks of presentation but not in the first week in patients who were admitted at ICU. Complete CT resolution was significantly more common in patients of younger age and lower initial CT severity scores.

A Multicenter Survey on the Trend of Chest CT Scan Utilization: Tracing the First Footsteps of COVID-19 in Iran.

BACKGROUND: Chest computed tomography (CT) scan has been used widely to diagnose COVID-19 in Iran. OBJECTIVES: To trace the footsteps of COVID-19 in Iran by exploring the trend in using chest CT scans and its economic impact on radiology departments. Methods: In this cross-sectional study, the number of imaging examinations from 33 tertiary radiology departments in 9 large cities of Iran was collected from September 23, 2019 to March 20, 2020 (Months 1 to 6) and the corresponding months in 2018-2019. RESULTS: A 50.2% increase was noted in the chest CT scan utilization in 2019-2020 compared to 2018-2019. This increase was +15%, +15%, +27%, +2%, +1% in Months 1-5 of 2019-2020, respectively. In Month 6 of 2019-2020, a 251% increase in the acquisition of chest CT scans was observed compared to the Month 6 of 2018-2019. Following negative balance of revenue from Month 1 to 5 with respect to the inflation rate, the total income in Month 6 was further 1.5% less than the same Month in 2018-19. CONCLUSION: The observed peak in chest CT utilization in Month 3 prior to the surge in Month 6 could be explained by the seasonal influenza. However, unawareness about an emerging viral disease, i.e. COVID-19, might have underutilized chest CT in Months 4 and 5 before the official announcement in Month 6. The unbalanced increase in the workload of radiology departments in the shortage of cardiothoracic radiologists with the simultaneous decrease in income initiated a vicious cycle that worsened the economic repercussions of the pandemic.

Evaluation of the relationship between inpatient COVID-19 mortality and chest CT severity score.

OBJECTIVES: There is scarce data available on the prognostic application of chest CT. The main purpose of this study was to evaluate the performance of a semi-quantitative CT severity score in identifying the risk of mortality in COVID-19 patients. METHODS: This retrospective cohort study was performed on 262 hospitalized COVID-19 patients. The CT severity score was assessed by two independent radiologists using a method previously used to score the severity of acute respiratory distress syndrome on thin slice lung CT. RESULTS: Multivariate regression analysis showed increasing odds of in-hospital death associated with older age, and the presence of coronary artery disease at the time of admission. The mean CT severity score was 7.5 in the survivor group and 14.5 in the deceased group. Overall, the lower zones were the most frequently affected sites in COVID-19. There was significant difference between the survivor and deceased groups regarding CT severity scores. Multivariate regression analysis showed increasing odds of in-hospital death associated with higher CT severity score at admission. CONCLUSIONS: Our results show that mortality was significantly higher in patients with higher CT severity score even after adjustment for clinical, demographics and laboratory parameters. However, this study is performed retrospectively and needs to be validated in a prospective study.