NIST paving the way for traceable measurements in the human body via MRI

A novel system that can calibrate medical imaging biomarkers could be paving the way for MRI to make precise, traceable measurements inside the human body, the National Institute of Standards and Technology (NIST) announced late this March.

“Physicians need highly accurate images for diagnosis and treatment decisions,” NIST officials said in a release. “Quantitative parameters measured by MRI need to be both accurate and have well-defined uncertainties before they can be used for clinical decision-making.”

What that means is MRI operators need to characterize their scanners and imaging protocols using traceable standards—namely those based around the International System of Units (SI)—and measure their machine’s accuracy using phantoms, or stand-in objects whose properties mimic certain tissues in the body.

NIST’s new NMR calibration service, based in its Boulder, Colorado, facilities, has the ability to test phantom materials before they hit the market. Customers initially send NIST 10-microliter samples of liquids they’re looking to use in the fabrication of phantoms, and NIST’s NMR system tests those samples three times at specified magnetic field strengths and temperatures.

The measured properties allow NIST traceability to SI, the release stated, as well as an analysis of different uncertainties in the measurements.

“When we deliver a NIST-traceable certificate, we give both the properties of the materials and an absolute uncertainty,” Stephen Russek, a NIST program scientist, said in the release. “It’s important to know the uncertainties in detail, because they propagate through the calibration chain. Our service is meant to provide a path to obtain better and lower uncertainties in human measurements.”

The NMR service currently measures two properties of the samples—proton spin relaxation times T1 and T2—but the researchers said they’re expanding the system to measure water diffusion, as well.

Russek said NIST’s system is unique in that it can quantify hard-to-measure biomarkers like white matter hyperintensity, which is related to the degeneration of nerves or myelin sheaths around them. Other, similar high-intensity regions can help predict early-onset Alzheimer’s and other cognitive disorders.

“Right now, there’s nobody who offers this measurement with SI traceability,” Russek said. “We’re the first and only operation to do so. Some biomarkers are very ambiguous and cannot be rigorously quantified unless you have this kind of traceability.”