Chest CT-based Assessment of 1-year Outcomes after Moderate COVID-19 Pneumonia

Abstract

Background: COVID-19 pneumonia may lead to pulmonary fibrosis in the long term. Chest CT is useful to evaluate changes in the lung parenchyma over time.

Purpose: To illustrate the temporal change of lung abnormalities on chest CT scans associated with COVID-19 pneumonia over 1 year.

Materials and methods: In this prospective study, patients previously hospitalized due to COVID-19 pneumonia who visited the radiology department of a tertiary care center for imaging follow-up were consecutively enrolled between March 2020 and July 2021. Exclusion criteria were acute respiratory distress syndrome, requirement of intubation and/or mechanical ventilation, pulmonary embolism, and any interstitial lung disease. High-resolution volumetric noncontrast chest CT scans were acquired at 3, 6, and 12 months from the first diagnosis and were compared with baseline CT scans. The imaging features analyzed were ground-glass opacity (GGO), consolidation, pleuroparenchymal band, linear atelectasis, bronchiectasis and/or bronchiolectasis, reticulation, traction bronchiectasis and/or bronchiolectasis, and honeycombing. The prevalence distribution of lung abnormalities was recorded at all time points.

Results: Eighty-four participants (56 men; mean age, 61 years ± 11 [SD]) were studied. GGOs and consolidations represented the main baseline lung abnormalities, accounting for a median severity score of 9 (IQR, 7-12.7; maximum possible score, 20), which indicates moderate lung involvement. The baseline prevalence of GGOs decreased from 100% to 2% of participants at 1 year, and that of consolidations decreased from 71% to 0% at 6 months. Fibrotic-like abnormalities (pleuroparenchymal bands, linear atelectasis, bronchiectasis and/or bronchiolectasis) were detected at 3 months (50% of participants), 6 months (42% of participants), and 1 year (5% of participants). Among these, pleuroparenchymal bands were the most represented finding. Fibrotic changes (reticulation and traction bronchiectasis and/or bronchiolectasis) were detected at 3-6 months (2%) and remained stable at 1 year, with no evidence of honeycombing. At 1 year, lung abnormalities due to COVID-19 pneumonia were completely resolved in 78 of 84 (93%) participants.

Conclusion: Residual lung abnormalities in individuals hospitalized with moderate COVID-19 pneumonia were infrequent, with no evidence of fibrosis at 1-year chest CT. © RSNA, 2022.

Graphical abstract

Figure 1:

High-resolution noncontrast chest CT findings in a 62-year-old man with COVID-19 pneumonia during 1-year follow-up. (A) Coronal section (multiplanar reconstruction) at baseline shows diffuse bilateral hazy ground-glass opacity (GGO) (lung severity score, 10 out of 20). (B) Representative axial section at baseline with evidence of GGO in the right lower lobe along with the sign of a dark bronchogram. No abnormalities are present in the left lower lobe for comparison (box). (C) Scan obtained at 3-month follow-up shows residual GGO. Consolidations are present in both lower lung lobes, likely due to transient disease worsening involving the right lower lobe. A small segmental bronchiectasis is appreciable in close proximity to a band-like consolidation in the left lower lobe (box). (D) Scan obtained at 1-year follow-up shows complete resolution of GGO and consolidations and disappearance of segmental bronchiectasis (box).

Figure 2:

High-resolution noncontrast chest CT findings in a 70-year-old man with COVID-19 pneumonia and previous mitral valve replacement during 1-year follow-up. (A) Archive control noncontrast CT axial section obtained 1 year before COVID-19 shows the absence of any focal or diffuse and/or infiltrative lung disease (box). (B) Baseline image obtained at the onset of COVID-19 pneumonia shows bilateral consolidations (box) in the lower lung lobes (lung severity score, 12 out of 20). (C) Image obtained at 6-month follow-up shows almost complete reabsorption of consolidations. Mild GGOs are detectable in the lower lobes, and there is evidence of linear atelectasis (box). (D) Image obtained at 1-year follow-up shows complete resolutoin of both GGOs and linear atelectasis (box).

Figure 3:

High-resolution noncontrast chest CT findings in a 68-year-old man with COVID-19 pneumonia during 1-year follow-up. (A) Representative coronal section obtained at baseline shows the presence of bilateral consolidations in the lower lung lobes with multiple sites of attachment to the costal pleura (lung severity score, 13 out of 20). (B) The same consolidations (box) are seen in the lower lung lobes on baseline axial section. (C) Discrete reduction of consolidations and mild ground-glass opacities are appreciable on the 3-month follow-up image. Parenchymal bands attached to the pleura are shown in the box. (D) Image obtained at 1-year follow-up shows complete resolution of lung abnormalities, with no evidence of parenchymal bands (box).

Figure 4:

High-resolution noncontrast chest CT findings in a 72-year-old man with COVID-19 pneumonia during 1-year follow-up. (A) Baseline axial section shows extensive hazy ground-glass opacities (GGOs) with dark bronchogram signs in the lower lung lobes (lung severity score, 12 out of 20). (B) Image obtained at 1-year follow-up shows incomplete resolution of areas of GGO and the presence of reticulation and multiple areas of medullary traction bronchiectasis and/or bronchiolectasis (arrows) with “corkscrew” features suggestive of architectural fibrotic distortion, as for an overlapping fibrosing organizing pneumonia and/or nonspecific interstitial pneumonia pattern.