Visible on chest CT scans, post-COVID-19 residual lung abnormalities, which affect up to 50% of patients who have had an infection requiring hospitalization, may be associated with persistent or progressive respiratory symptoms and are often related to changes in respiratory function tests. But unlike other non-infectious abnormalities, they tend to stabilize or regress over time, indicating that they are non-progressive and only post-infectious in nature.
Published in the journal Radiology, the paper is the result of a multi-society consensus statement developed by 21 chest radiologists belonging to the European Society of Thoracic Imaging (ESTI), the Society of Thoracic Radiology and the Asian Society of Thoracic Radiology (ASTR), validated by international expert pulmonologists and led by Professor Anna Rita Larici of the Università Cattolica in Rome, Associate of Diagnostic Imaging in the Department of Radiological and Hematological Sciences and head of the Thoracic Diagnostics Unit affiliated with the Thoracic and Cardiovascular Radiology Unit - directed by Prof. Luigi Natale - at the Advanced Radiology Center of the Department of Diagnostic Imaging and Radiation Oncology - directed by Prof. Evis Sala - of the Fondazione Policlinico Universitario A. Gemelli IRCCS in Rome.
The consensus was reached through a two-stage investigation process, which aims to standardize the indications, acquisition, and reporting of chest CT scans in patients with post-COVID-19 residual lung abnormalities.
BACKGROUND
COVID-19 can cause persistent or worsening symptoms after infection, described as post-COVID disorder or "long COVID," and it is estimated that about 6% of people who have had COVID-19 suffer from this condition. Among patients hospitalized for acute COVID-19, an average of 50% have alterations on chest CT scans and 25% have restrictive pulmonary function abnormalities four months after infection. Radiologists face several important challenges in managing this patient population.
Professor Larici explains: "These include differentiating between persistent residual lung abnormalities from COVID-19—such as ground glass opacity—and any fibrotic alterations, as well as assessing the temporal evolution of these findings. It is essential to distinguish post-COVID-19 residual lung abnormalities from interstitial lung abnormalities (ILA) and interstitial lung diseases (ILD), particularly fibrotic ones, as they have very different clinical implications. Post-COVID-19 abnormalities generally stabilize over time, while ILAs and ILD can progress and have a poor prognosis," she points out.
RECOMMENDATIONS
Professor Larici explains: The key recommendations emerging from this consensus include the use of chest CT for patients with persistent or progressive respiratory symptoms 3 months after infection, the use of low-dose CT for follow-up examinations, the use of the Fleischner Society glossary of terms to describe post-COVID-19 lung abnormalities correctly and avoid the term interstitial lung abnormality (ILA). She adds: "Using the right name is essential, she explains, in order to refer the patient for appropriate follow-up and avoid misinterpreting post-COVID-19 lung abnormalities as an early manifestation of interstitial lung disease. Therefore, the term 'post-COVID-19 residual lung abnormalities' should always be used in these patients, and references to pulmonary fibrosis, which is a very different and, above all, progressive disease, should always be avoided." This consensus statement will help harmonize radiological practice and research for the considerable number of patients affected.
"Ours is a best practice guideline, a consensus statement that emerged to promote a uniform approach to the diagnosis of lung changes in CT scans of patients with persistent long COVID symptoms: it guides the radiologist to address clinical practice, like deciding when to perform a chest CT scan (only in cases of persistent symptoms and functional abnormalities), how to perform the CT scan, and when to repeat it, avoiding improper patient management, which would initiate a diagnostic process for pulmonary fibrosis with numerous CT scans and other tests that are unnecessary for long COVID patients; in fact, she concludes, only a very small percentage of patients have permanent post-COVID-19 fibrosis. Although we don't have definitive estimates, these cases seems to be extremely rare."
