What is the relationship between steatosis (fatty liver disease) and fibrosis as measured by FibroScan (transient elastography)?

From the Guidelines

Steatosis and fibrosis are closely related liver conditions that can be assessed simultaneously using FibroScan technology, with steatosis often preceding and contributing to the development of fibrosis, and their relationship is crucial for proper disease staging and treatment planning. The Controlled Attenuation Parameter (CAP) score measures the degree of fat accumulation in the liver, while liver stiffness measurement (LSM) evaluates fibrosis. According to the most recent guidelines, a stepwise approach using blood-based scores, such as the fibrosis-4 index (FIB-4), and sequentially, imaging techniques like transient elastography, is suitable to rule-out/in advanced fibrosis, which is predictive of liver-related outcomes 1.

Key Points to Consider

• The presence of significant steatosis (CAP >248 dB/m) alongside elevated liver stiffness (>7-8 kPa) suggests more advanced liver disease requiring medical intervention.
• FibroScan provides valuable non-invasive assessment of both conditions, though interpretation requires caution as severe steatosis can artificially elevate fibrosis measurements.
• A low cutoff of 8 kPa for LSM using vibration-controlled transient elastography (VCTE) has a 93% sensitivity to exclude advanced fibrosis, and patients with LSM <8.0 kPa can be considered low risk for clinically significant fibrosis 1.
• The relationship between steatosis and fibrosis is progressive, with chronic liver fat accumulation triggering inflammatory processes that can lead to hepatocyte damage and the development of fibrosis.

Clinical Implications

• Understanding the relationship between steatosis and fibrosis is crucial for proper disease staging, treatment planning, and monitoring progression or improvement in response to lifestyle modifications or medications.
• The use of FibroScan technology, in conjunction with other diagnostic tools, can help identify patients at risk of advanced liver disease and guide treatment decisions.
• Lifestyle modification, including weight loss, dietary changes, and physical exercise, as well as optimal management of comorbidities, is advised for adults with metabolic dysfunction-associated steatotic liver disease (MASLD) 1.

From the Research

Relationship Between Steatosis and Fibrosis on FibroScan

• The relationship between steatosis and fibrosis on FibroScan is complex, with studies suggesting that steatosis can affect the accuracy of liver stiffness measurements (LSM) in patients with chronic hepatitis B and nonalcoholic fatty liver disease (NAFLD) 2, 3.
• However, other studies have found that the controlled attenuation parameter (CAP) on FibroScan is a reliable tool for evaluating liver steatosis, with high concordance with liver biopsy results 4.
• The accuracy of FibroScan in assessing steatosis and fibrosis has been evaluated in several studies, with area under the receiver operating characteristic curves (AUROCs) ranging from 0.70 to 0.89 for CAP and 0.77 to 0.89 for LSM 5, 4, 6.
• The optimal cutoff values for CAP and LSM have been established for different stages of steatosis and fibrosis, with values ranging from 247 dB/m to 337 dB/m for CAP and 8.2 kPa to 13.6 kPa for LSM 5, 4.

Factors Affecting FibroScan Measurements

• Steatosis has been shown to affect the accuracy of LSM, with higher LSM results observed in patients with steatosis, even in the same stage of liver fibrosis 2, 3.
• The type of probe used on FibroScan, such as the M or XL probe, can also affect the accuracy of measurements, with the XL probe providing better results in obese patients 2, 5.
• Other factors, such as alanine aminotransferase (ALT) levels, can also affect the accuracy of LSM, with higher ALT levels resulting in falsely-high LSM results 2.

Clinical Applications of FibroScan

• FibroScan has been shown to be a useful tool for predicting patient outcomes, including the development of hepatocellular carcinoma, portal hypertension, and postoperative complications in patients with liver disease 2, 6.
• The use of FibroScan in clinical practice can help physicians estimate both fibrosis stage and patient prognosis, allowing for more accurate diagnosis and treatment of liver disease 6.