Computed tomography (CT) abnormalities are reported among a substantial proportion of patients after hospitalization with COVID-19.
More than half of people hospitalized with COVID-19 experience chest imaging abnormalities after recovery from acute infection, according to a review led by investigators at National Jewish Health in Denver.
The review, “CT of Postacute Lung Complications of COVID-19,” published in Radiology, analyzed computed tomography (CT) abnormalities in patients recovering from COVID-19, citing data from more than 100 published articles.
“A substantial proportion of previously hospitalized survivors of SARS-CoV-2 infection will have abnormality on CT, more commonly in those with more severe acute infection,” David Lynch, MB, radiologist at National Jewish Health told Diagnostic Imaging. “The most common abnormalities are ground glass opacity, parenchymal or subpleural bands, reticular abnormality, evidence of fibrotic abnormality, and air trapping.”
The review noted that 14% of people infected with SARS-CoV-2 will develop dyspnea, tachypnea, hypoxia or lung opacities.
Post-Acute Sequelae of COVID-19, also referred to as Long COVID, has been a concern for a subset of patients, with symptoms including loss of taste or smell, fatigue and shortness of breath. Risk factors include increasing age, body mass index, female sex and higher number of symptoms during acute COVID-19.
Post-COVID lung disease has been a focus given the incidence of pulmonary involvement during acute illness and persistent respiratory symptoms during recovery, the authors noted. Predictors include ICU admission, mechanical ventilation, higher inflammatory markers, longer hospital stay and diagnosis of acute respiratory distress syndrome (ARDS). Post-COVID lung disease may be the result of ARDS, mechanical ventilation or injury from the virus.
The review called for detailed, high-resolution CT in all patients with dyspnea following COVID-19, including helical supine inspiratory chest CT acquisition with contiguous or overlapping thin-section reconstruction and expiratory thin-section CT.
The review described a subset of patients with CT abnormalities including ground glass abnormalities and subpleural bands at 3 months after acute infection. At 6 months, some changes suggestive of fibrosis were noted.
“An important aspect was the varying definition of fibrotic abnormalities in published papers,” Lynch said. “The standard radiologic definition of fibrosis on CT includes traction bronchiectasis, honeycombing, and architectural distortion. However, many of the published papers include features such as parenchymal or subpleural bands, which may represent scars or atelectasis rather than diffuse fibrosis.”
“Precise radiologic description is important; the term fibrosis should be reserved for those with clear evidence of fibrosis,” Lynch added. “Also, comparison with acute-phase imaging is important to understand the temporal course of abnormality.”
Among the literature reviewed, a study of 51 hospitalized patients found that 54% had persistent abnormalities on CT four weeks after discharge. At three months, residual abnormalities were reported among 42% of patients in another study that included 52 subjects, 25% of whom were never hospitalized. A study of 48 patients who required mechanical ventilation, only 4% had normal imaging at three months. A study of 114 patients found CT evidence of fibrotic-like changes among 35% at six months.
Possible treatments under consideration include corticosteroids along with drugs such as nintedanib and pirfenidone to mitigate or prevent fibrosis
Further research is needed to determine the persistence of post-COVID lung disease over time, the impact on pulmonary function and quality of life, and to inform treatment and prevention.