Calculate Liver Fat Fraction
Estimate hepatic fat fraction using MRI signal inputs. This tool is for education and quick estimation, not diagnosis.
What is liver fat fraction?
Liver fat fraction is the percentage of fat within liver tissue. It is commonly used to evaluate hepatic steatosis (fatty liver), including metabolic dysfunction-associated steatotic liver disease (MASLD). A higher percentage usually indicates more fat accumulation in the liver.
In modern imaging workflows, MRI-PDFF (proton density fat fraction) is often used because it provides a quantitative estimate of liver fat. While this calculator does not replace full radiology software, it helps you understand the underlying math.
How this liver fat fraction calculator works
1) Fat/Water Signal Method
When separate fat and water signal values are available, fat fraction is estimated as:
Fat Fraction (%) = 100 × Fat Signal / (Fat Signal + Water Signal)
This is intuitive and useful when your workflow directly reports fat and water components.
2) In-phase / Out-of-phase Approximation
If only in-phase and out-of-phase MRI signals are available, this approximation can be used:
Fat Fraction (%) ≈ 100 × (SIin − SIout) / (2 × SIin)
This is a simplified method. Advanced clinical pipelines may correct for T1, T2*, iron deposition, and other confounders.
How to interpret the result
Interpretation varies by institution and protocol, but a common practical guide is:
- < 5%: Generally considered within normal range
- 5% to < 15%: Mild steatosis range
- 15% to < 30%: Moderate steatosis range
- ≥ 30%: Severe steatosis range
Always interpret liver fat fraction with clinical context, including liver enzymes, metabolic risk, fibrosis assessment, and imaging quality.
Best practices for accurate inputs
- Use ROI values from a consistent liver segment protocol.
- Avoid vessels, bile ducts, and artifacts when selecting measurement regions.
- Use the same scanner settings when tracking changes over time.
- If comparing visits, keep acquisition and post-processing methods consistent.
Clinical context and limitations
This calculator is educational. A true diagnostic report should come from validated clinical imaging workflows and physician interpretation. In some cases (for example, high iron burden), simple out-of-phase methods may under- or over-estimate actual fat fraction.
If your estimated value is elevated, discuss next steps with a healthcare professional. Management typically focuses on root causes such as insulin resistance, obesity, dyslipidemia, alcohol intake, medication effects, and other metabolic factors.
FAQ
Is this a diagnostic tool?
No. It provides an estimate for educational and screening support only.
Can I use ultrasound numbers here?
No. The formulas here are MRI signal-based and not directly compatible with ultrasound scoring systems.
Why might my value be negative with in/out-of-phase data?
Negative values can occur from noise, protocol mismatch, or confounders. The calculator floors negative estimates to 0% and flags this as a caution.