From the Guidelines
Fatty liver disease can be assessed through a combination of blood tests, imaging studies, and sometimes liver biopsy, with a stepwise approach using blood-based scores and imaging techniques being suitable to rule-out/in advanced fibrosis, as recommended by the most recent guidelines 1.
Initial Evaluation
Initial evaluation typically includes liver function tests such as ALT, AST, and GGT, which may be elevated in fatty liver disease. Complete metabolic panels and lipid profiles are also important to assess for metabolic risk factors.
Imaging Studies
Imaging studies like ultrasound, which can detect moderate to severe fatty infiltration, are often the first-line diagnostic tool due to their non-invasive nature and accessibility.
- CT scans and MRI, particularly MRI-PDFF (proton density fat fraction) and MR elastography, offer more precise quantification of liver fat and assessment of fibrosis.
- FibroScan (transient elastography) is another non-invasive option that measures both liver stiffness and fat content.
Definitive Diagnosis
For definitive diagnosis, especially to distinguish between simple steatosis and steatohepatitis or to stage fibrosis, liver biopsy remains the gold standard, though it's typically reserved for cases where the diagnosis remains unclear or when advanced disease is suspected, as noted in earlier guidelines 1.
Importance of Early Detection
These tests are essential because fatty liver disease is often asymptomatic until advanced stages, yet early detection allows for lifestyle interventions and treatment that can prevent progression to cirrhosis or liver failure. The most recent guidelines emphasize the importance of case-finding strategies for MASLD with liver fibrosis, using non-invasive tests, in individuals with cardiometabolic risk factors, abnormal liver enzymes, and/or radiological signs of hepatic steatosis 1.
From the Research
Tests to Assess Fatty Liver
- Non-invasive assessment of fatty liver is crucial due to the dangers and complications of liver biopsy 2
- Imaging modalities such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) can be used to assess liver steatosis and detect focal liver lesions (FLLs) 3
- MRI is generally superior to ultrasound and CT for detection and characterization of FLLs in patients with fatty liver 3
- Non-invasive diagnostic tests for non-alcoholic fatty liver disease (NAFLD) include ultrasonography (US), CT, and MRI, which can reliably diagnose hepatic steatosis 4
- Chemical shift-encoded (CSE)-MRI is the best imaging indicator for early liver fat detection 4
- Clinical prediction rules and blood-based biomarkers, such as NAFLD fibrosis score, FIB-4 index, and BARD score, can be used to identify patients at high risk of NASH and advanced fibrosis 5
- Combining blood biomarkers can improve diagnostic accuracy, and more expensive tests such as FibroTest or ELF are more specific for detection of patients with significant and advanced fibrosis 5
Non-Invasive Imaging Methods
- US is widely available and radiation-free but cannot examine the entire liver 4
- CT is readily available and helpful for detection and risk classification, but exposes users to radiation 4
- MRI can measure liver fat percentage with magnetic resonance imaging proton density fat fraction (MRI-PDFF) and is expensive and time-consuming 4
Blood-Based Biomarkers
- NAFLD fibrosis score and FIB-4 index are cost-effective and highly sensitive tools to exclude patients with advanced fibrosis 5
- FibroTest or ELF are more specific for detection of patients with significant and advanced fibrosis 5
- Recent efforts have concentrated on "omics" approaches for developing and validating novel biomarkers 5