Diffuse Fatty Infiltration

1. Pathogenesis:

• A reversible process in which triglyceride accumulates diffusely in hepatocytes causing abnormal appearance on imaging. Normally, less than 5% of the liver is composed of fat. In diffuse fatty infiltrated liver, fat can make up to 50% of the liver tissue.
   
• Commonly seen in acute or chronic alcohol abuse (most common), obesity, diabetes, cystic fibrosis, tetracycline, steroids, chemotherapy, malnutrition, and hyperalimentation.
   
• Clinically, patients are asymptomatic. Liver can be enlarged but without splenomegaly.
   
• Removal of offending agents reverses the process.

2. Radiographic findings:

• U/S: the liver has increased focal or diffuse echogenicity when compared to the surrounding organs such as the kidneys.

• Noncontrast CT: the liver looks hypodense to the spleen due to fatty infiltration, making the hepatic vasculature more prominent.

• MRI: the most sensitive and specific technique for detecting hepatic fat infiltration but is primarily used for focal fat infiltration.