Prevalence of Hepatic Steatosis in Adults Presenting to the Emergency Department Identified by Unenhanced Chest CT

Abstract

This study aimed to investigate the prevalence of hepatic steatosis in racially diverse adults presenting to the emergency department at a tertiary healthcare system in the United States using attenuation values on unenhanced computed tomography (CT) as the reference standard. The utility of known risk factors for predicting the presence of hepatic steatosis was assessed. Additionally, reporting of hepatic steatosis in original radiology reports was evaluated. For 381 consecutive adults (193 women and 188 men; mean age 55.2 ± 17.2 years), hepatic (left medial, left lateral, right anterior, and right posterior) and splenic (upper, middle, and lower) CT attenuation values (Hounsfield units) were obtained by drawing a 1 cm² region of interest on unenhanced chest CT obtained in the emergency department for any indication. Multiple attenuation criteria for steatosis, including liver thresholds and liver and spleen attenuation comparison, were applied. Relevant clinical risk factors were recorded and compared against a liver/ spleen attenuation ratio of ≤ 1.1 to include all individuals with steatosis in the analysis. Mean liver attenuation was 59.5 ± 10.4 HU. The prevalence of hepatic steatosis ranged from 5-35.4% depending on the CT attenuation criterion used (5%, liver attenuation ≤ 40 HU; 6.3%, liver attenuation ≤ (spleen attenuation - 10 HU); 16.8%, liver attenuation ≤ spleen attenuation; 34.1%, liver attenuation ≤ (spleen attenuation + 5 HU); 35.4%, liver attenuation/ spleen attenuation ≤ 1.1). The prevalence of hepatic steatosis was higher in males compared to females (P = 0.01, 42% vs 29%) and age 40-65 years when compared to the rest (P = 0.03, 43.5% vs 32.2%), but similar across different racial (P = 0.55), ethnic (P = 0.78) groups. Overweight status (body mass index >25) and hypertension were sensitive indicator for steatosis (sensitivity = 60.7% and 60.5%) but were highly nonspecific (specificity = 41.9% and 49.2%). Other clinical risk factors, such as diabetes, dyslipidemia, alcohol overuse, and hepatitis, were more specific (specificity = 62.2%-93.9%) but highly insensitive (sensitivity = 7.5%-40.3%). 63% (12/19) radiology reports mentioned the presence of moderate-to-severe hepatic steatosis but only 11.1% (15/135) of them mentioned the presence of mild hepatic steatosis. Unenhanced chest CT can be used to assess hepatic steatosis for individuals presenting to the emergency department and provide a non-invasive means for opportunistic screening.