NIST Traceability in MRI
The foundation of quantitative imaging: linking your scanner's measurements to international standards
NIST traceability provides an unbroken chain of measurements connecting your MRI scanner to the fundamental standards maintained by the National Institute of Standards and Technology (NIST) in the United States. This ensures that quantitative measurements are absolute, reproducible, and comparable across any scanner, site, or time period.
Why Traceability Is Essential
Without SI-traceable calibration, quantitative MRI measurements can vary significantly between scanners and over time. A T1 value, T2 value, or ADC measurement is only meaningful when it's traceable to a known reference standard.
With NIST-traceable phantoms, you establish a direct measurement chain from your scanner to international standards—making your quantitative data absolute, comparable, and clinically actionable.
The Chain of Traceability
SI Base Units
The International System of Units (SI) provides the fundamental measurement standards recognised worldwide. For MRI, this includes units of time (seconds), length (metres), and temperature (kelvin) that define relaxation times, diffusion coefficients, and other quantitative parameters.
Foundation: These universally agreed standards ensure that measurements mean the same thing in every laboratory and clinic worldwide.
NIST Characterisation Services
NIST operates calibrated NMR systems directly traceable to SI units. These systems measure MRI properties—T1, T2, and apparent diffusion coefficient (ADC)— with the lowest achievable uncertainties, establishing reference values that serve as national measurement standards.
NIST Special Publication 250-97: Magnetic Resonance Relaxometry (T1 and T2) characterisation service for aqueous manganese chloride solutions.
NIST Special Publication 250-100: Apparent Diffusion Coefficient (ADC) characterisation service for polyvinylpyrrolidone (PVP) solutions.
GSP Manufacturing & NIST Characterisation
Gold Standard Phantoms manufactures bulk batches of each solution type (e.g., specific manganese chloride or PVP concentrations). A sample from each batch is sent to NIST for characterisation, where NIST measures the MR properties using their calibrated reference systems and issues a detailed report with measured values and uncertainties.
Our Process: Each solution batch is characterised by NIST across multiple temperatures (typically 0°C to 37°C). Vials are filled from these NIST-characterised batches. Since a phantom may contain multiple different solutions (e.g., 24 different vial types), it includes samples from multiple NIST-characterised batches—each traceable to NIST's measurements.
Your Phantom & Scanner Calibration
Each GSP phantom ships with documentation identifying which NIST-characterised batch was used for each vial position. The NIST characterisation reports provide the measured values, uncertainties, and temperature dependencies for each solution batch. When you scan the phantom, you can calibrate your scanner's measurements against these known reference values.
Complete the Chain: By calibrating your scanner to these NIST-traceable values, your clinical measurements become part of the unbroken chain back to SI base units—ensuring absolute, comparable results.
GSP's Commitment to Measurement Excellence
Every Batch, Directly from NIST
As a UCL spinout working closely with the UK's National Physical Laboratory and NIST, Gold Standard Phantoms has made direct NIST characterisation the foundation of our quality system.
- Every solution batch sampled and sent to NIST for characterisation
- Complete NIST reports with measured values and uncertainty budgets for each batch
- Temperature-dependent values covering clinical temperature ranges (0°C to 37°C)
- Phantom documentation identifying batch provenance for each vial
- 18-month certification validity from characterisation date
Look for this badge on all GSP products
Our NIST-Traceable Phantom Materials
T1 & T2 Relaxometry
Aqueous manganese chloride solutions with NIST-characterised T1 and T2 relaxation times at multiple temperatures and field strengths (1.5T and 3.0T).
Reference: NIST SP 250-97
Concentrations: 12 different MnCl₂ concentrations covering clinically relevant T1 ranges from ~190ms to ~2300ms
Certification: Valid for 18 months from characterisation date
Apparent Diffusion Coefficient
Aqueous polyvinylpyrrolidone (PVP) solutions with NIST-characterised ADC values, T1, and T2 at temperatures from 0°C to 37°C at 3.0T.
Reference: NIST SP 250-100
Concentrations: 10 different PVP concentrations (0% to 50%) covering ADC ranges from ~0.3 to ~2.0 × 10⁻³ mm²/s
Certification: Valid for 18 months from characterisation date
MultiSample Phantom Series
Our MultiSample phantoms hold up to 24 pre-filled vials in standardised configurations for relaxometry, diffusion, or mixed applications—all using NIST-traceable solutions.
Explore MultiSample SeriesNIST Pre-Filled Vials
Purchase individual NIST-traceable vials for custom phantom configurations or replacement of existing standards—available in both T1/T2 and ADC solutions.
Explore NIST Pre-Filled VialsWhy NIST Traceability Matters
Absolute Measurements
Your quantitative values—whether measuring tumour ADC, tissue T1, or cartilage T2— are referenced to international standards, not arbitrary scanner-specific units.
Longitudinal Consistency
Track true biological changes over time without uncertainty about whether differences reflect scanner drift, software updates, or actual tissue changes.
Multi-Site Comparability
Combine data across multiple institutions, scanner manufacturers, and field strengths with confidence that measurements are on the same absolute scale.
Clinical Decision Support
Establish absolute thresholds for diagnosis and treatment response that are valid across your entire patient population and applicable to published research.
Regulatory Compliance
Meet FDA, EMA, and MHRA requirements for quantitative biomarker validation with documented SI-traceable measurement chains and uncertainty budgets.
Research Reproducibility
Publish quantitative findings that other researchers can validate and reproduce on their own systems, advancing the field through reliable data.
Real-World Applications
Diffusion-Weighted Imaging
In stroke imaging, tumour characterisation, and prostate cancer detection, ADC values are critical for diagnosis. NIST-traceable calibration ensures that diagnostic thresholds established at one site work reliably at another, and that ADC trends tracked over time reflect true tissue changes.
Quantitative T1 & T2 Mapping
For cardiac imaging, liver iron quantification, and musculoskeletal applications, absolute T1 and T2 values enable tissue characterisation and disease staging. NIST traceability allows direct comparison to published reference values and ensures consistency across scanner upgrades and multi-centre trials.
Pharmaceutical Development
Drug trials increasingly use quantitative MRI as endpoints. NIST-traceable phantoms provide the quality control needed to pool data across trial sites, satisfy regulatory requirements, and demonstrate that observed changes represent true treatment effects rather than measurement variability.
Technical Details
Understanding Measurement Uncertainty
Every NIST characterisation report includes not just the measured value but also its uncertainty—a quantitative statement of the measurement's reliability. This allows you to:
- Calculate your scanner's measurement precision relative to known references
- Determine if observed changes exceed measurement uncertainty
- Meet regulatory requirements for documented measurement traceability
- Properly interpret small differences in clinical or research data
Example: ADC Uncertainty Budget
A typical NIST ADC characterisation provides expanded uncertainties less than 2% (k=2), accounting for temperature variations, measurement repeatability, and systematic effects. This allows you to distinguish true ADC changes as small as 3-5% with statistical confidence.
Ready to Establish Measurement Traceability?
Join leading research institutions and clinical centres worldwide using NIST-traceable phantoms for quantitative MRI