European Radiology

, Volume 22, Issue 5, pp 1075–1082

Specificity of unenhanced CT for non-invasive diagnosis of hepatic steatosis: implications for the investigation of the natural history of incidental steatosis

  • Perry J. Pickhardt
  • Seong Ho Park
  • Luke Hahn
  • Sung-Gyu Lee
  • Kyongtae T. Bae
  • Eun Sil Yu

DOI: 10.1007/s00330-011-2349-2

Cite this article as:
Pickhardt, P.J., Park, S.H., Hahn, L. et al. Eur Radiol (2012) 22: 1075. doi:10.1007/s00330-011-2349-2



To determine a highly specific liver attenuation threshold at unenhanced CT for biopsy-proven moderate to severe hepatic steatosis (≥30% at histology).


315 asymptomatic adults (mean age ± SD, 31.5 ± 10.1 years; 207 men, 108 women) underwent same-day unenhanced liver CT and ultrasound-guided liver biopsy. Blinded to biopsy results, CT liver attenuation was measured using standard region-of-interest methodology. Multiple linear regression analysis was used to assess the relationship of CT liver attenuation with patient age, gender, BMI, CT system, and hepatic fat and iron content.


Thirty-nine subjects had moderate to severe steatosis and 276 had mild or no steatosis. A liver attenuation threshold of 48 HU was 100% specific (276/276) for moderate to severe steatosis, with no false-positives. Sensitivity, PPV and NPV at this HU threshold was 53.8%, 100% and 93.9%. Hepatic fat content was the overwhelming determinant of liver attenuation values, but CT system (P < 0.001), and hepatic iron (P = 0.035) also had a statistically significant independent association.


Unenhanced CT liver attenuation alone is highly specific for moderate to severe hepatic steatosis, allowing for confident non-invasive identification of large retrospective/prospective cohorts for natural history evaluation of incidental non-alcoholic fatty liver disease. Low sensitivity, however, precludes effective population screening at this threshold.

Key Points

Unenhanced CT liver attenuation is highly specific for diagnosing moderate/severe hepatic steatosis.

Unenhanced CT can identify large cohorts for epidemiological studies of incidental steatosis.

Unenhanced CT is not, however, effective for population screening for hepatic steatosis.


Non-alcoholic fatty liver disease (NAFLD)Hepatic steatosisComputed tomographyNatural historyNon-alcoholic steatohepatitis (NASH)

Copyright information

© European Society of Radiology 2011

Authors and Affiliations

  • Perry J. Pickhardt
    • 1
  • Seong Ho Park
    • 2
  • Luke Hahn
    • 1
  • Sung-Gyu Lee
    • 3
  • Kyongtae T. Bae
    • 5
  • Eun Sil Yu
    • 4
  1. 1.Department of RadiologyUniversity of Wisconsin School of Medicine & Public HealthMadisonUSA
  2. 2.Department of Radiology and Research Institute of RadiologyUniversity of Ulsan College of Medicine, Asan Medical CenterSeoulKorea
  3. 3.Division of Hepatobiliary Surgery and Liver Transplantation, Department of SurgeryUniversity of Ulsan College of Medicine, Asan Medical CenterSeoulKorea
  4. 4.Department of PathologyUniversity of Ulsan College of Medicine, Asan Medical CenterSeoulKorea
  5. 5.Department of RadiologyUniversity of PittsburghPittsburghUSA