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).AJR Am J Roentgenol 2012

Hepatic steatosis affects up to 30% of the general population in Western countries, with rising prevalence linked to obesity, diabetes, and metabolic syndrome.Radiology 2021 Prevalence exceeds 70% in patients with type 2 diabetes and reaches 90% in those undergoing bariatric surgery.

Most cases remain asymptomatic and are detected incidentally on ultrasound or other imaging.World J Gastroenterol 2014 Symptomatic patients may report right upper quadrant discomfort, fatigue, or elevated liver enzymes.

Steatosis results from impaired fat metabolism, with triglycerides accumulating in >5% of hepatocytes.Eur J Radiol 2007 Macrovesicular steatosis predominates, featuring a single large cytoplasmic fat droplet displacing the nucleus.

• Hyperechoic liver parenchyma (”bright liver”) compared to kidney or spleenRadioGraphics 2006
• Grading:

• Unenhanced CT: Liver attenuation <40 HU absolute or >10 HU lower than spleenAJR Am J Roentgenol 2012
• Contrast-enhanced: Focal sparing appears hyperdense relative to steatotic parenchyma (gallbladder fossa, segment IV)AJR Am J Roentgenol 2012
• Dual-energy CT improves quantificationRadiology 2021

• Chemical shift imaging (in/out-of-phase): Signal dropout on opposed-phase images (>5% fat)Radiology 2021
• Proton density fat fraction (PDFF): Gold standard for quantificationRadiology 2021
• Spectroscopy: Measures fat fraction directly

Management targets underlying causes (weight loss, diabetes control).World J Gastroenterol 2014 Steatosis alone carries excellent prognosis without fibrosis; NASH risks progression to cirrhosis (20-30%).

• Glycogen storage disease (US: hyperechoic but vessels clear)RadioGraphics 2006
• Acute hepatitis (diffuse hypoechoic)Eur J Radiol 2007
• Focal fat sparing/deposition mimics massRadioGraphics 2006
• Iron overload (high attenuation on CT)AJR Am J Roentgenol 2012

Medical Disclaimer: Portions of this content were AI-generated to facilitate rapid knowledge synthesis. Radiologists and clinicians must independently verify all information against peer-reviewed literature, institutional protocols, and patient-specific factors before clinical application.