Computed tomography signs of the possible aspergillosis in the dynamic observation of patients with COVID-19

BACKGROUND: Aspergillosis of the lungs, which occurs against the background of COVID-19, develops as a life-threatening complication, especially in patients with a severe disease and those treated in intensive care units. Mortality rates vary significantly in the published materials, with inexplicably high levels in some of them. All the studies are united in the conclusion that, in the absence of a timely diagnosis and treatment, mortality can reach 100%. Obtaining a biological material for the laboratory diagnostics is often difficult. In such cases, computed tomography of the lungs serves as an informative instrumental study to exclude or confirm the presence of the mycotic lung damage, including aspergillosis, against the background of COVID-19. Thus, the systematization, generalization and analysis of CT changes in the lungs of COVID-associated pulmonary aspergillosis are required.

AIM: Determination of CT signs of a possible addition of pulmonary aspergillosis in patients with COVID-19 during a dynamic follow-up.

METHODS: The analysis of the case histories of 646 patients, in whom the results of CT monitoring of the lung condition for at least 2 months were obtained, was carried out. The total number of CT examinations is 5279, the average number of studies per patient is 8. The main group consisted of 144 patients. The leading inclusion criterion was the presence of radiological signs atypical for COVID-19, suspicious for fungal complications. The control group included 502 patients with the lung changes characteristic of COVID-19. All CT scans of the chest organs were performed without intravenous administration of a contrast agent in accordance with the standard scanning protocols.

RESULTS: The analysis of the obtained images revealed the primary signs suspicious for COVID-associated aspergillosis, which can be conditionally divided into typically bronchogenic and conventionally non-bronchogenic signs. Of the total number of patients in the main group, the bronchogenic signs (single and multiple intracellular foci, «peribronchial cuffs», bronchiectasis) were noted in 56 (38.89%) patients, and in 43 (76.79%) of them, the transformation into signs characteristic of a fungal lesion was revealed. Conventionally non-bronchogenic primary signs were identified in 88 (61.11%) patients. In the process of studying the dynamics of signs suspicious for COVID-associated aspergillosis, CT-signs typical of fungal lesions were obtained in 93 (64.58%) patients. Consolidations as a primary sign and a sign of transformation from foci were encountered in one time interval. This finding made it possible to collect all the signs of COVID-associated aspergillosis in a combined timing scheme.

CONCLUSION: The features of the clinical course of the disease in patients with COVID-19 do not allow us to confidently determine co-infection, such as aspergillosis. There are also difficulties in isolating the pathogen culture. Consequently, the role of computed tomography in identifying the semiotics of possible aspergillosis as a complication of COVID-19 is increasing. COVID-associated pulmonary aspergillosis on CT scans is characterized by signs of damage to the respiratory tract with the subsequent formation of cavitary structures.