Brain imaging via MRIs may soon be enhanced with simple sugar instead of conventional metal complexes. A new study found that glucose, a simple and common form of sugar, is a safer and more accurate alternative for tumor imaging.
Magnetic resonance imaging (MRI) is a technique that uses magnetic field and radio waves to build a picture of organs and structures inside the body. Although MRIs can be performed alone, clinicians often rely on use of agents that enhance the contrast of the image to better detect the details. An agent commonly used for this purpose is gadolinium, which is a naturally occurring metal. Gadolinium MRI contrast agents are useful, but it has known toxicities, including side effects in kidney patients. Furthermore, gadolinium can build-up in the body as deposits in the brain, especially for patients who require repeat MRIs.
To overcome this challenge, a German research team sought to exploit a tumor’s biology. Mainly, they took advantage of the fact that most tumors consume more sugar than normal tissues. Thus, they turned to glucose as an MRI contrast agent.
Since glucose is naturally present in the body, the team had to devise a way to make the glucose agent inside tumors more prominent. For this, they turned to an ultrahigh field scanner with 7 Tesla magnetic field strength, which is powerful enough to visualize the signals in a tumor.
"Our glucose MRI does not require any radioactivity and therefore does not involve any radiation exposure for the patient," said Dr. Daniel Paech, a physician and physicist at the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), and the study’s lead author.
Using glucose could big safety and efficacy potential. According to a few recent studies, gadolinium from traditional MRIs can deposit in bone and the brain, suggesting that residuals could cause long-term harm. And from an efficacy perspective, glucose may yield better tumor visualization because it is taken up by the tumor cells more readily, and it can also penetrate the blood-brain barrier more efficiently than gadolinium due to its smaller size. This means that glucose-enhanced MRIs should detect close to 100 percent of high-grade tumors, in contrast to the 70 to 80 percent detected by gadolinium MRIs.
Still, they have some unanswered questions regarding the new technology. "We do not know yet how the shares of measured glucose are distributed between vessels and extracellular spaces on the one hand and the cell interior on the other," said radiologist Heinz-Peter Schlemmer, a study co-author. "If we can confirm that substantial signal levels originate from glucose in the cell interior, this would be important additional information for tumor imaging and functional MRI. This could enhance therapy planning and monitoring."
Additional source: German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) via Science Daily