Clinical Report: Radiologists' Diagnostic Accuracy in Differentiating Post-COVID-19 Lung Residuals from ILD

Overview

This study assessed the ability of radiologists to distinguish post-COVID-19 residual lung abnormalities from interstitial lung abnormalities (ILA) using chest CT scans. Fifteen multinational radiologists evaluated 60 cases, demonstrating moderate diagnostic performance with challenges in differentiating fibrotic ILA from post-COVID-19 residuals.

Background

By March 2024, approximately 10% of the global population had confirmed SARS-CoV-2 infection, with some patients developing persistent lung CT abnormalities known as post-COVID-19 residuals. These residual abnormalities can resemble interstitial lung abnormalities (ILA), which may progress to pulmonary fibrosis. Differentiating post-COVID-19 residuals from ILA is clinically important due to their differing long-term prognoses. Radiologists often must rely solely on imaging features without clinical history to make this distinction, but their diagnostic accuracy in this context has not been well studied.

Data Highlights

Key Findings

• Radiologists used a 5-point scale to differentiate post-COVID-19 residual abnormalities from ILA without clinical history.
• Diagnostic performance was evaluated on 20 post-COVID-19 residual and 40 ILA cases (20 fibrotic, 20 non-fibrotic).
• Post-COVID-19 residual abnormalities predominantly showed ground-glass opacities with peribronchovascular distribution and perilobular opacities.
• Fibrotic ILA cases showed reticulation, traction bronchiolectasis, and non-emphysematous cysts with subpleural and basal distribution.
• Non-fibrotic ILA cases showed ground-glass opacities with subpleural and basal distribution.
• Radiologists demonstrated moderate ability to distinguish post-COVID-19 residuals from ILA, with particular difficulty differentiating fibrotic ILA from post-COVID-19 residual abnormalities.

Clinical Implications

Radiologists should be aware of the overlapping imaging features between post-COVID-19 residual lung abnormalities and ILA, especially fibrotic subtypes. Incorporating clinical history of prior SARS-CoV-2 infection remains important but may not always be available; thus, cautious interpretation of CT findings is warranted. Awareness of characteristic imaging patterns can aid in more accurate differentiation, potentially impacting patient management and prognosis.

Conclusion

Radiologists exhibit moderate diagnostic performance in distinguishing post-COVID-19 residual lung abnormalities from interstitial lung abnormalities based on CT imaging alone. Continued efforts to refine imaging criteria and incorporate clinical data are essential to improve diagnostic accuracy.

References

1. Global SARS-CoV-2 Infection Data 2024 -- Cumulative Infection Statistics
2. Post-COVID-19 Lung Abnormalities -- Radiologic Features and Prognosis
3. Fleischner Society Position Paper 2018 -- Interstitial Lung Abnormalities Definitions