Researchers at the Tokyo University of Science have applied a new imaging technique in a way that may allow clinicians to assess liver fat content without having to take biopsies. Called near-infrared hyperspectral imaging, the method can highlight fat distribution in liver tissue, potentially helping clinicians to diagnose and assess conditions such as nonalcoholic fatty liver disease (NAFLD).
NAFLD involves excessive fat deposition in the liver and can lead to liver failure. As the name suggests, this isn’t caused by alcohol abuse, but risk factors such as type 2 diabetes and high cholesterol play a role. At present, the standard technique to assess the liver for its fat content is to obtain a biopsy. This isn’t much fun for the patient, so a less invasive approach would be welcome.
“Lipid distribution in the liver provides crucial information for diagnosing fatty liver-associated liver diseases including cancer, and therefore, a noninvasive, label-free, quantitative modality is needed,” said Kyohei Okubo, a researcher involved in the study. “We have developed a method to visualize the distribution of lipids in the liver using a near-infrared spectral imaging technique that incorporates machine learning.”
Previously, researchers have used near-infrared hyperspectral imaging to image atherosclerotic plaques in the blood vessels of rabbits, and so these Japanese researchers hypothesized that it might be useful to assess the distribution of fatty acids in the liver.
The team tested the technique with mice that ate a normal diet or a high-fat diet, and were able to visualize the lipid distribution throughout their livers. They could even generate maps that showed the gradients of lipid density. A technique called the Folch extraction method helped the researchers to quantitatively measure the actual lipid content of each liver, and they found that their measurements obtained using near-infrared hyperspectral imaging correlated closely with these values.
The results suggest that the technique may be valuable in assessing suspected fatty liver in human patients, without the need for biopsy. For their study, the researchers imaged the mouse livers after they were removed from the mice, but it may be possible to image the liver in situ, minimally invasively.
Study in Biomedical Optics Express: Visualization of quantitative lipid distribution in mouse liver through near-infrared hyperspectral imaging