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).¹⁾

Hepatic steatosis affects up to 30% of the general population in Western countries, with rising prevalence linked to obesity, diabetes, and metabolic syndrome.²⁾ 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.³⁾ 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.⁴⁾ Macrovesicular steatosis predominates, featuring a single large cytoplasmic fat droplet displacing the nucleus.

• Hyperechoic liver parenchyma (”bright liver”) compared to kidney or spleen⁵⁾
• Grading:

• Unenhanced CT: Liver attenuation <40 HU absolute or >10 HU lower than spleen⁶⁾
• Contrast-enhanced: Focal sparing appears hyperdense relative to steatotic parenchyma (gallbladder fossa, segment IV)⁷⁾
• Dual-energy CT improves quantification⁸⁾

• Chemical shift imaging (in/out-of-phase): Signal dropout on opposed-phase images (>5% fat)⁹⁾
• Proton density fat fraction (PDFF): Gold standard for quantification¹⁰⁾
• Spectroscopy: Measures fat fraction directly

Management targets underlying causes (weight loss, diabetes control).¹¹⁾ Steatosis alone carries excellent prognosis without fibrosis; NASH risks progression to cirrhosis (20-30%).

• Glycogen storage disease (US: hyperechoic but vessels clear)¹²⁾
• Acute hepatitis (diffuse hypoechoic)¹³⁾
• Focal fat sparing/deposition mimics mass¹⁴⁾
• Iron overload (high attenuation on CT)¹⁵⁾

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.