Introduction
Coronavirus disease 2019 (COVID-19), which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been a threat to global public health [1]. Reverse transcription-polymerase chain reaction (RT-PCR) test is the gold standard for the molecular diagnosis of the disease [2]. Although it is a highly specific test, in clinical use it shows a variable sensitivity, which arises the need of other tools to support the diagnosis. Since chest computed tomography (CT) is widely available and can contribute to fast pneumonia diagnosis, it plays an important role in the diagnosis and management of COVID-19 patients [2–5].
COVID-19 demonstrates a wide clinical spectrum ranging from asymptomatic infection to severe pneumonia with acute respiratory distress syndrome, multiple organ failure, and death, with many patients being hospitalized [6–8]. Older age, comorbidities including hypertension, diabetes, cardiovascular disease, respiratory disease, and laboratory examinations such as white blood cells (WBC), aspartate aminotransferase (AST), creatinine, lactate dehydrogenase (LDH), and d-dimer have been reported to imply the progression of COVID-19 [9, 10]. Chest CT findings have been shown to be associated with severe or critical COVID-19 pneumonia as well as with the different stages of the disease [11, 12]. Although the involvement of the respiratory system is common, liver injury may occur especially in patients with severe COVID-19 [13].
Changes of hepatic density on unenhanced CT scans can occur in diffuse liver diseases, whether as a decrease in steatosis or an increase in hemochromatosis [14, 15]. Other entities that may alter hepatic density on CT include drug-induced toxicity, acute hepatitis, acute toxic hepatic injury, cirrhosis, and radiation-induced injury [15]. It has been reported that unenhanced CT scans demonstrate diffuse hypoattenuating areas in the liver of patients with viral acute liver failure [16]. Liver-to-spleen ratio (L/S) on unenhanced CT has been used to discriminate hepatic steatosis [17]. Thus, L/S may be helpful in the evaluation of liver injury as it reflects the changes of hepatic attenuation. Given the lack of information in the literature for the assessment of abdominal imaging findings in COVID-19 patients, which may be related to the limited evaluation of the upper abdomen on unenhanced chest CT scans, we aimed to investigate the changes in L/S during the course of disease. The purpose of this study is to correlate the L/S, clinical, laboratory findings, and lung CT scores of COVID-19 patients who had two consecutive chest CT scans.