Long-term effects of COVID-19 in patients according to the functional lung imaging in radiation therapy

Abstract

Background: the majority of patients who experienced COVID-19, lung disorders persist for a long term. It remains unclear how reversible they are and what the clinical and radiation predictors of these changes are. Aim: to determine the consequences of pneumonia caused by the SARS-CoV-2 virus in patients who experienced COVID-19 during the period of 2020–2021; to evaluate possible clinical and radiation predictors of these changes and their reversibility. Patients and Methods: the article presents the analyzed results of radiation studies (computed tomography (CT), single-photon emission computed tomography (SPECT)), spirometry and diffusing capacity of the lungs for carbon monoxide (DLCO) performed in 68 patients who had COVID-19 during the period of 2020–2021 and complained of persistent shortness of breath, fatigue and disability. Results: 1–2 years after, there was a decrease in the bronchial patency to 39.2±4.5%pred in 63% of patients with mild COVID-19, which correlated (rs>0.92) with a decrease in microcirculation (MC) over 50% and mosaic attenuation (rs>0.77), air trapping (rs>0.89) and bronchiolectasis (rs>0.64). In mixed ventilatory defects (MEF75 to 46.8±3.6% of predicted, DLCO 62.4±3.1% of predicted), there were significant MC disorders over 70%, corresponding to zones of focal pneumosclerosis (rs>0.93). In the severe disease course, single areas of "frosted glass" were detected in 13% of patients, while mosaic attenuation and air trapping were detected in 34%, which was accompanied by a decrease in MEF75 to 37.4±3.7% of predicted. During a decrease in DLCO to 52.4±2.2% of predicted, there were a compaction of the interstitial by the type of usual interstitial pneumonia of small extent (65%), consolidation areas (34%), pneumosclerosis areas (54%), platelike atelectasis (31%), bronchiectasis (26%), signs of bronchiolitis obliterans (42%), and pulmonary hypertension development (38%). According to the single- photon emission computed tomography data, there were significant disorders of the MC. Irreversible changes were detected in lung areas with an inadequate perfusion of more than 50%, observed 6 months after the disease, and subsequently, after 1 year or more. Conclusions: a comprehensive functional lung imaging in radiation therapy increases the efficacy of clinical examination of patients in the postcovid period. The following type of patients need a comprehensive radiation monitoring: patients over 60 y.o., patients who had a severe COVID-19; patients who have respiratory complaints over 1 year, regardless of the COVID-19 severity. Microcirculation disorders over 50% detected 6 months after the disease are a predictor of changes in the lung parenchyma and may indicate long-term disease consequences. KEYWORDS: postcovid syndrome, microcirculation, computed tomography of the lungs, ventilation, artificial intelligence. FOR CITATION: Zolotnitskaya V.P., Speranskaya A.A., Kuzubova N.A. et al. Long-term effects of COVID-19 in patients according to the functional lung imaging in radiation therapy. Russian Medical Inquiry. 2022;6(7):360–366 (in Russ.). DOI: 10.32364/2587-6821- 2022-6-7-360-366.