A new portable sensor can accurately measure patients’ hydration levels using a technique known as nuclear magnetic resonance (NMR) relaxometry. Such a device could be useful for not only dialysis patients but also people with congestive heart failure, as well as athletes and elderly people who may be in danger of becoming dehydrated.

A noninvasive hydration sensor is based on the same technology as MRI. (Credit: Lina Colucci, Andrew Hall/MIT)

The portable device is based on the same technology as magnetic resonance imaging (MRI) scanners but can obtain measurements at a fraction of the cost of MRI, and in much less time, because there is no imaging involved.

The NMR measurements were able to detect the presence of excess fluid in the body before traditional clinical signs — such as visible fluid accumulation below the skin — were present. The sensor could be used by physicians to determine when a patient has reached their true dry weight, and this determination could be personalized at each dialysis treatment.

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