Stiff Competition

Organ stiffness, often measured through techniques like ultrasound elastography, serves as a crucial indicator of various underlying health conditions, most notably liver disease or failure. Liver diseases encompass a wide range of conditions, including hepatitis, cirrhosis, fatty liver disease, and liver cancer, among others. The seriousness of these conditions varies, but they all share the potential to cause significant harm if left untreated. As such, for many individuals, it is crucial to keep watch over changes in organ stiffness.

Acute liver failure can occur suddenly, often as a result of a viral infection, drug toxicity, or ischemia, and can rapidly progress to life-threatening complications if not addressed swiftly. Early detection of liver disease or failure is paramount in initiating timely treatment plans to mitigate further damage and improve outcomes. Ultrasound elastography has emerged as a valuable tool in this regard, offering a non-invasive means of assessing organ stiffness, including liver fibrosis, which often accompanies liver disease.

In the intensive care unit, ultrasound elastography is frequently employed following liver transplants to monitor the condition of the newly transplanted organ. However, despite its utility, this technique is limited by the periodic nature of scans conducted by technicians who manually move a wand over the tissue to collect data. The intervals between scans creates gaps in monitoring, potentially allowing problems to go undetected for some time. Such lapses in surveillance can lead to delayed intervention and poorer outcomes.

Continuous monitoring would alleviate these problems and allow for earlier detection of changes in organ stiffness, but unfortunately, present technologies rely on manual work performed by medical professionals. A team led by researchers at MIT has demonstrated that there is a better option that allows for collecting continuous ultrasound elastography data, however. They have developed a small, wearable sticker that can collect a steady stream of ultrasound measurements without the guidance of a trained technician. Initial experiments showed that the device can recognize the early signs of acute liver failure.

When worn on the skin over an organ to be monitored, the team’s 25-millimeter-square chip utilizes 128 miniaturized piezoelectric transducers to transmit sound waves into the body and capture the reflected sound waves. The ultrasound sticker is attached to the skin using a hydrogel which not only keeps the device in place, but is also engineered to allow sound waves to pass through it with almost no interference. When the sound waves return to the skin patch, they can be analyzed to determine the amount of vibration they induce in the organ being monitored. This vibration can then be correlated with organ stiffness.

Early experiments with this device were conducted in rats. Over a period of 48 hours, the rats were monitored for signs of liver failure. It was shown that clear signs of failure could be detected using the ultrasound sticker. When examining tissue samples, the researchers proved that the data they were observing reflected actual changes in the organs under observation.

As a next step, the team is adapting their system for use with humans in the intensive care unit, where it could prove valuable in monitoring transplant patients. As it currently stands, the sticker must be wired to external components to supply power and resources for interpretation of the data, but the researchers plan to explore the possibility of making the device fully self-contained so that it can be worn in everyday life — even at home. If that goal is achieved, they see the possibility of patients wearing multiple stickers for other purposes, like monitoring vital signs, or even scanning for tumors.