COVID-19 impact on liver attenuation by computed tomography: a retrospective cohort study

Abstract

Introduction. A high prevalence of decreased liver attenuation has been shown in patients with COVID-19, but there is no unequivocal estimate of the effect of disease severity on it. There has been no evaluation of the liver status both before and after COVID-19.Aim: To study the impact of COVID-19 on liver attenuation by two computed tomography (CT) scans: before and after the onset of pneumonia.Material and Methods. Retrospective cohort study was performed. Data of COVID-19 outpatients were analyzed. Inclusion criteria: two chest CT scans, alanine aminotransferase (ALT), aspartate aminotransferase (AST) blood values, polymerase chain reaction to verify SARS-CoV-2. A PCR positive result was a criterion for the COVID-19 presence. The criteria for absence were a negative PCR result on an oropharyngeal swab for SARS-CoV-2, and absence of a lung lesion on both CT scans. The endpoint was a decrease in liver density of more than 10 HU. Two comparison groups have been identified following the achievement of the endpoint. Liver attemuation was analyzed by automatic segmentation, with values less than 40 HU being considered pathologic.Results. Data from 499 patients were selected and two comparison groups were formed: group 1 – liver attenuation decreased by more than 10 HU in the dynamics and group 2 – control group. Liver attenuation on baseline CT was 8.4 HU higher (95% confidence interval (CI) 5.5-11.2; p-value < 0.001) in group 1 versus group 2. Regression analysis showed an association between a decrease in liver attenuation 10 HU or more on follow-up and low liver attenuation on primary CT (odds ratio 0.26 (95% CI 0.1-0.69), p-value = 0.002). Other factors had no significant effect on the liver attenuation change.Conclusion. COVID-19 has no effect on liver attenuation, which may indicate that there is no significant effect of the virus on liver status.