Segmental distribution of hepatic steatosis on opportunistic low-dose computed tomography: a Couinaud-based analysis
Year: 2026
Type: article
Study design: Observational Study
Abstract: Background: Hepatic steatosis is commonly and incidentally detected on nonenhanced computed tomography (CT) as areas of low attenuation. Hepatic steatosis is recognized as an independent predictor of cardiovascular disease and type 2 diabetes mellitus (DM), underscoring the clinical significance of its detection and characterization. Low-dose CT (LDCT) performed for lung cancer screening offers a unique opportunity for opportunistic evaluation of hepatic steatosis. The objective of this study is to measure CT attenuation across all eight Couinaud liver segments in patients with incidentally detected hepatic steatosis on lung cancer screening LDCT, and to identify clinical correlates of steatosis. Methods: This retrospective, single-center study evaluated hepatic steatosis among patients who underwent LDCT for lung cancer screening between 2019 and 2024; patients with steatosis and available 1.5 mm soft-tissue reconstructions comprised the analytic cohort for segmental analysis. Steatosis was defined as mean liver attenuation <40 Hounsfield units (HU) on unenhanced CT. Mean CT attenuation (HU) was measured in each Couinaud segment on soft-tissue 1.5 mm unenhanced reconstructions and normalized to intrathoracic tracheal air to reduce interscan variability related to scanner calibration and acquisition parameters. Segmental differences were assessed by repeated-measures analysis of variance (ANOVA) with Tukey-Kramer post-hoc correction. Associations between mean liver HU and clinical variables [age, gender, coronary artery calcification (CAC) score, body mass index, DM] were evaluated using t-tests, and multivariable linear regression. Results: , P=0.01). Mean liver attenuation was -30.9±30.5 HU (range, -109.2 to +27.6 HU). Segmental attenuation ranged from -27.1±30.8 HU in segment 1 (caudate lobe) to -34.0±30.9 HU in segment 7. Repeated-measures ANOVA demonstrated significant segmental variation (P<0.001); segment 1 showed higher attenuation than segments 3, 4A, 4B, 6, 7, and 8 (all Tukey-adjusted P<0.05), indicating relative caudate sparing. Segments 7 and 8 had the lowest attenuation. Within-patient variability was modest (mean standard deviation: 4.91±1.94 HU), though a subset showed substantial heterogeneity. In multivariable linear regression, older age (β=+0.16/year, P=0.001) and female sex (β=+1.51, P=0.03) were independently associated with higher liver attenuation, while DM was associated with lower attenuation (β=-2.44, P=0.001). Conclusion: In this exploratory, single-center study, the mean attenuation of segments 7 and 8 combined correlated strongly with whole-liver attenuation and may represent a practical candidate proxy for opportunistic screening. Validation in a larger study is needed before this two-segment measurement approach is adopted for routine use.
Authors: Ingrid Galvis, Jonathan Alis, Mary Salvatore
Institution: Jacobi Medical Center
Language: English
Subfield: Hepatology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7223819032