Elastography vs. Fibrosis Scan: Understanding the Differences
Elastography is a broader imaging technique category that measures tissue stiffness, while FibroScan is a specific brand-name device that uses transient elastography, which is one type of elastography technology. 1, 2
Types of Elastography Technologies
Ultrasound-Based Elastography
Transient Elastography (TE)
- FibroScan is the most common commercial implementation
- Uses a mechanical pulse to generate shear waves
- Measures liver stiffness at a single point
- Results provided in kilopascals (kPa)
- Requires at least 10 valid measurements with an interquartile range/median ≤30% 1, 2
- Limitations:
- Higher failure rates in obese patients (requires XL probe)
- Cannot be used in patients with ascites
- Affected by food intake, inflammation, and congestion 1
Acoustic Radiation Force Impulse (ARFI) Techniques 3
Point Shear Wave Elastography (pSWE)
- Measures stiffness at specific points
- Can be integrated with conventional ultrasound imaging
2D Shear Wave Elastography (2D-SWE)
- Provides real-time color maps of tissue stiffness
- Examines larger areas than point measurements
- Lower failure rates than point SWE 1
3D Shear Wave Elastography
- Newest technology providing volumetric assessment
Strain Elastography
- Measures tissue deformation in response to compression
- More qualitative than quantitative 3
MR Elastography (MRE)
- Uses MRI technology to measure liver stiffness throughout the entire liver
- Higher accuracy for intermediate stages of fibrosis compared to ultrasound methods
- Better performance in obese patients and those with ascites
- Can evaluate for hepatocellular carcinoma simultaneously
- Limitations: not accurate in patients with hepatic iron deposition 1
Key Differences Between Elastography and FibroScan
| Feature | Elastography (General) | FibroScan (Specific) |
|---|---|---|
| Definition | Umbrella term for various techniques that measure tissue stiffness | Brand name for a specific device that uses transient elastography |
| Technology Range | Includes TE, ARFI, SWE, MRE | Uses only transient elastography |
| Imaging Capability | Varies (some provide 2D/3D images) | No imaging data, only stiffness measurements |
| Tissue Coverage | Varies (MRE examines entire liver) | Examines only a small portion of liver tissue |
| Clinical Setting | Hospital radiology departments (for MRE, 2D-SWE) | Portable, can be used at bedside or in clinic |
| Cost | Varies (MRE most expensive) | Relatively lower cost |
| Operator Dependency | Varies (ARFI is operator dependent) | Less operator dependent but requires training |
Clinical Applications and Performance
Both elastography techniques and FibroScan are used to:
- Assess liver fibrosis non-invasively
- Monitor disease progression
- Evaluate treatment response
- Predict risk of decompensation in cirrhosis 1
MR elastography shows superior diagnostic performance for:
- Intermediate stages of fibrosis
- Obese patients
- Patients with ascites 1
FibroScan (transient elastography) is:
Practical Considerations
- FibroScan failure rates: approximately 5% overall, higher in obese patients 4
- MRE failure rates: approximately 4.3%, mainly in patients with iron overload 1
- Both techniques should be interpreted in conjunction with clinical findings and laboratory tests 2
- Factors affecting accuracy include:
- Acute inflammation
- Extrahepatic cholestasis
- Passive congestion
- Recent food intake 1
In clinical practice, the choice between different elastography techniques depends on availability, patient characteristics, cost considerations, and the specific diagnostic question being addressed.