Longitudinal Changes in Liver Fat Content in Asymptomatic Adults: Hepatic Attenuation on Unenhanced CT as an Imaging Biomarker for Steatosis

OBJECTIVE. The objective of this study was to evaluate changes in liver fat content over time in asymptomatic adults and to investigate the factors that may influence these changes. MATERIALS AND METHODS. Liver attenuation on unenhanced CT images of 1022 asymptomatic adults (556 women and 466 men; mean age at the time of the index CT examination, 56.7 years) was retrospectively measured on initial and surveillance CT colonography screening examinations (mean [± SD] interval, 5.5 ± 0.8 years). Changes in liver attenuation (expressed as Hounsfield units) were assessed according to various factors, including body mass index (BMI), age, and sex. RESULTS. Mean liver attenuation was 60.3 HU on the index CT scan and 58.4 HU on the 5-year follow-up CT scan (p < 0.0001). Changes in liver attenuation greater than 10 HU, 5–10 HU, and less than 5 HU were observed in 187 (18%), 212 (21%), and 623 (61%) individuals, respectively. Changes in attenuation greater than 10 HU were negative (i.e., fattier liver) in 130 of 18...