Computed tomography scans in the evaluation of fatty liver disease in a population based study: the multi-ethnic study of atherosclerosis

Rationale and objectives: Fatty liver disease is a common clinical entity in hepatology practice. This study evaluates the prevalence and reproducibility of computed tomography (CT) measures for diagnosis of fatty liver and compares commonly used CT criteria for the diagnosis of liver fat.

Materials and methods: The study includes 6814 asymptomatic participants from a population-based sample. The ratio of liver-to-spleen (L/S) Hounsfield units (HU) <1.0 and liver attenuation <40 HU were used for diagnosing and assessing the severity of liver fat content. Participants with heavy alcohol intake (>7 drinks/week for women and >14 drinks/week for men) were excluded. Final analysis was performed on participants where images of both liver and spleen were available on the scans.

Results: The overall prevalence of fatty liver (4175 subjects included in final analysis) was 17.2% (using L/S ratio <1.0), with 6.3% (with <40 HU cutoff) of the population having moderate to severe steatosis (>30% liver fat content). The prevalence was high in participants with dyslipidemia (70.4%), hypertension (56.8%), and obesity (53%). Diabetic patients had 24.1% prevalence of fatty liver. The prevalence provided by L/S ratio <1.0 (17.2%) was comparable to prevalence provided by <51 HU (17.3%), whereas prevalence obtained by <40 HU (6.3%) cutoff corresponded to L/S ratio of <0.8 (6.5%). The measurements of liver and spleen HU attenuations were highly reproducible (0.96, 0.99 and 0.99, 0.99 for intra- and inter-reader variability, respectively) in a sample of 100 scans.

Conclusion: Fatty liver can be reliably diagnosed using nonenhanced CT scans.