Fatty liver disease is a condition in which fat builds up in the liver, which leads to inflammation and eventually fibrosis, a buildup of scar tissue that can cause jaundice and liver cirrhosis, and eventually liver failure. Because there are often no symptoms, it is not easy to find fatty liver disease or fibrosis. However, MIT engineers have now developed a diagnostic tool, based on nuclear magnetic resonance (NMR), that could be used to detect both conditions.
Their study, “A portable single-sided magnetic-resonance sensor for the grading of liver steatosis and fibrosis,” is published in the journal Nature Biomedical Engineering.
“Low-cost noninvasive diagnostic tools for staging the progression of nonalcoholic chronic liver failure from fatty liver disease to steatohepatitis are unavailable. Here, we describe the development and performance of a portable single-sided magnetic-resonance sensor for grading liver steatosis and fibrosis using diffusion-weighted multicomponent T2 relaxometry,” noted the researchers.
Using a mouse model of nonalcoholic fatty liver disease, the sensor achieved overall accuracies of 92% (Cohen’s kappa, κ = 0.89) and 86% (κ = 0.78) in the ex vivo grading of steatosis and fibrosis.
“Since it’s a noninvasive test, you could screen people even before they have obvious symptoms of compromised liver, and you would be able to say which of these patients had fibrosis,” explained Michael Cima, the David H. Koch Professor of Engineering in MIT’s department of materials science and engineering, a member of MIT’s Koch Institute for Integrative Cancer Research, and the senior author of the study.
The device, which is portable and small enough to fit on a table, uses NMR to measure how water diffuses through tissue, which can reveal how much fat is present.
The researchers had the idea of adapting a detector that they had previously developed to measure hydration levels before and after patients undergo dialysis. That detector measures fluid volume in patients’ skeletal muscle by using NMR to track changes in the magnetic properties of hydrogen atoms of water in the muscle tissue. The researchers thought that a similar detector could be used for identifying liver disease because water diffuses more slowly when it encounters fatty tissue or fibrosis.
“If you watch how the magnetization changes, you can model how fast the protons are moving,” Cima said. “Those cases where the magnetization doesn’t go away very fast would be ones where the diffusivity was low, and they would be the most fibrotic.”
The results are obtained in about 10 minutes, but researchers are working on improving on obtaining results faster. The sensor scans to a depth of about 6 mm below the skin, which is enough to monitor the mouse liver or human skeletal muscle. The researchers are now working on designing a new version that can penetrate deeper below the tissue, to allow them to test the liver diagnosis application in human patients.
Fibrosis can’t be reversed, but it slowed down through dietary changes and exercise. This diagnostic tool may even lead to new drug development efforts, because it can help identify patients with fibrosis and monitor their response to potential new treatments.
“The use of T2 relaxometry as a sensitive measure in fully automated low-cost magnetic-resonance devices at the point of care would alleviate the accessibility and cost limits of magnetic-resonance imaging for diagnosing liver disease and assessing liver health before liver transplantation,” concluded the researchers.
