  Purpose: Automatic methods are required for the early detection of hepatic
steatosis to avoid progression to cirrhosis and cancer. Here, we developed a
fully automated deep learning pipeline to quantify hepatic steatosis on
non-contrast enhanced chest computed tomography (CT) scans. Materials and
Methods: We developed and evaluated our pipeline on chest CT images of 1,431
randomly selected National Lung Screening Trial (NLST) participants. A dataset
of 451 CT scans with volumetric liver segmentations of expert readers was used
for training a deep learning model. For testing, in an independent dataset of
980 CT scans hepatic attenuation was manually measured by an expert reader on
three cross-sectional images at different hepatic levels by selecting three
circular regions of interest. Additionally, 100 randomly selected cases of the
test set were volumetrically segmented by expert readers. Hepatic steatosis on
the test set was defined as mean hepatic attenuation of < 40 Hounsfield unit.
Spearman correlation was conducted to analyze liver fat quantification accuracy
and the Cohen's Kappa coefficient was calculated for hepatic steatosis
prediction reliability. Results: Our pipeline demonstrated strong performance
and achieved a mean dice score of 0.970 for the volumetric liver segmentation.
The spearman correlation of the liver fat quantification was 0.954 (P <0.0001)
between the automated and expert reader measurements. The cohen's kappa
coefficient was 0.875 for automatic assessment of hepatic steatosis.
Conclusion: We developed a fully automatic deep learning-based pipeline for the
assessment of hepatic steatosis in chest CT images. With the fast and cheap
screening of hepatic steatosis, our pipeline has the potential to help initiate
preventive measures to avoid progression to cirrhosis and cancer.
