Fatty liver disease, also known as hepatic steatosis, occurs when excess fat accumulates within liver cells. This condition can interfere with the liver’s normal functions, including processing food and waste materials. Ultrasound is a widely used imaging technique to detect and assess fat buildup. It is a non-invasive diagnostic tool, helping identify the condition early.
Understanding Fatty Liver Disease
Fatty liver disease has two primary forms: Non-Alcoholic Fatty Liver Disease (NAFLD) and Alcoholic Fatty Liver Disease (AFLD). NAFLD, now often referred to as Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD), is the more common type, not caused by heavy alcohol consumption. It is linked to conditions like obesity, type 2 diabetes, insulin resistance, and metabolic syndrome (including high triglycerides, high blood pressure, and a large waist size).
AFLD develops due to excessive alcohol intake. Both types involve fat accumulation, but their underlying causes differ. Fatty liver often remains without noticeable symptoms initially, making ultrasound particularly helpful for detection. Early detection can allow for interventions before more severe liver damage occurs.
How Ultrasound Identifies Fatty Liver
Ultrasound uses high-frequency sound waves that are sent into the body and reflected back to create images of internal organs, including the liver. These sound waves behave differently when they encounter various tissue types. When fat deposits accumulate in the liver, they alter how these sound waves travel and reflect.
A fatty liver appears brighter or whiter than normal liver tissue on an ultrasound image, a characteristic known as increased “echogenicity.” Fat also causes decreased sound wave penetration, a phenomenon called attenuation. This attenuation can make it harder to visualize deeper structures within the liver, such as blood vessels and the diaphragm. Quantitative ultrasound techniques, such as controlled attenuation parameter (CAP) and ultrasound attenuation imaging (ATI), measure this attenuation to quantify liver fat.
What Ultrasound Images Reveal
Radiologists interpreting a fatty liver ultrasound image look for several visual cues. One indicator is comparing the liver’s brightness to the adjacent right kidney, known as hepatorenal contrast. In a fatty liver, the liver often appears noticeably brighter than the kidney.
Another observation involves the clarity of blood vessels within the liver and the diaphragm. As fat increases, these structures may become less distinct or even obscured due to sound wave attenuation. The degree of increased brightness and obscured structures can help estimate steatosis severity, often categorized as mild, moderate, or severe. While ultrasound is effective for detecting moderate to severe steatosis, its sensitivity for mild cases can be lower.
Life After a Fatty Liver Diagnosis
Receiving a fatty liver diagnosis often prompts questions about what comes next. Fatty liver disease, particularly NAFLD, is often reversible through lifestyle modifications. These changes aim to reduce liver fat and improve overall liver health.
Common recommendations include a healthy diet emphasizing fruits, vegetables, whole grains, and healthy fats, while limiting processed foods, sugary drinks, and excessive red meat. Regular physical activity and weight management are also encouraged; even modest weight loss (3% to 5% of body weight) can show benefits. Follow-up with a healthcare provider is important for monitoring and determining if further evaluations, such as blood tests or additional imaging, are necessary.