Hepatic steatosis, also known as fatty liver disease, refers to abnormal accumulation of fat within hepatocytes, most commonly manifesting as non-alcoholic fatty liver disease (NAFLD).

Hepatic steatosis affects up to 30% of the general population in Western countries 1.

• Hyperechoic liver parenchyma (”bright liver”) compared to kidney or spleen 1
• Grading 2:

• Unenhanced CT: Liver attenuation <40 HU absolute or >10 HU lower than spleen 3
• Contrast-enhanced: Focal sparing appears hyperdense relative to steatotic parenchyma (gallbladder fossa, segment IV) 3
• Dual-energy CT improves quantification 4

• Chemical shift imaging (in/out-of-phase): Signal dropout on opposed-phase images (>5% fat) 4
• Proton density fat fraction (PDFF): Gold standard for quantification 4

• Glycogen storage disease (US: hyperechoic but vessels clear) 1
• Iron overload (high attenuation on CT) 3

1. RadioGraphics 2006: Fatty Liver 2. Ultrasound Med 2019 3. AJR Am J Roentgenol 2012 4. Radiology 2021

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