Powered by

MRI without contrast agents? Yes, with sugar!

Scientists from the German Cancer Research Center (DKFZ), in collaboration with colleagues from Heidelberg University Hospital, have been able to visualize brain cancer using a novel MRI method. They use a simple sugar solution instead of conventional contrast agents, which can have side effects in the body.

Visualization of brain cancer by conventional contrast agents (left) and by the novel glucose MRI method (right). © Paech D, et al. T1ρ-weighted dynamic glucose enhanced MRI in the human brain. Radiology (in press) ; RSNA.

In magnetic resonance imaging (MRI), contrast agents are used to enhance the imaging of tissue structures. While they enhance signals in blood vessels and in spaces between cells, they do not reach the interior of the cell. By contrast, glucose is taken up and then broken down in the body cells. Tumor cells are particularly hungry for glucose in order to feed their high energy needs. By observing glucose metabolism activity it may therefore be possible to identify solid tumors or very aggressively growing tumor areas. Radiologists and physicists from the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) in Heidelberg have now succeeded in employing this novel type of imaging.

Glossary

  • Pathogenity is the ability to cause a disease. One differentiates between human, animal, and plant pathogens which specifically cause a disease in either humans, animals or plants.
  • A tumour is a swelling of a tissue caused by abnormal cell growth, which can be benign or malignant. Benign tumours are local swellings, whereas malign tumours may seed off and spread into other tissues, causing secondary growths (metastases).
  • Radiology is a section in medicine that deals with the application of rays (e.g. x-rays, gamma rays, electrons) for diagnostic, therapeutic and scientific purposes.
  • Magnetic resonance imaging (MRI) is an imaging technique to visualize structures that are located within the body. The MRI technique is based on the use of magnetic fields and allows the generation of very detailed cross section images of the human body.
  • Positron emission tomography (PET) is an imaging technique used to display structures as well as biochemical and physiological processes in the body. This technique is based on the distribution of a radioactive labelled substance in the organism, which then emits positrons and therefore can be detected by a scintillation counter.
  • Polyehylene (abbrevation: PE) is the polymer of ethylene. It belongs to the thermoplastic synthetics.
  • Glucose is a monosaccharide (or simple sugar). It can be found in almost all sweet fruits. Glucose is an important intermediate of the carbohydrate metabolism.

Conventional MRI is based on measuring the signals from protons in water. Since over 60 percent of our body is made up of water, this delivers a clear picture. Glucose is found at much lower levels in our body. In order to make it visible, the DKFZ researchers are therefore using an ultrahigh field scanner with 7 Tesla magnetic field strength and a special method to reinforce the glucose signal distinctly and selectively. This makes it possible to obtain sufficient signal strength in order to visualize changes in glucose levels in brain tissue after injection of a glucose solution.

The underlying physical principle of this method is called magnetization transfer effect. While this effect has been known for decades, it hasn't been possible so far to use it for glucose imaging in humans. In magnetization transfer, the signal from glucose protons is transferred to bodily water, which is measured in MRI. The effect is proportional to the local glucose level, thus reflecting regional changes in glucose levels. The amount of glucose needed for glucose measuring corresponds to about five sugar cubes.

In the present work, physicist Patrick Schuenke and physician and physicist Daniel Paech have been able to observe the changes of glucose signals in healthy brain regions as well as pathogenic changes in human brain cancer.

For decades now, scientists have used another measuring method, called positron emission tomography (PET), to visualize elevated glucose uptake in tumors. However, this method requires radioactively labeled glucose molecules. "Our glucose MRI does not require any radioactivity and therefore does not involve any radiation exposure for the patient," said Paech, who is the first author of the publication.

The glucose MRI project is a collaboration of DKFZ scientists from the groups led by Peter Bachert, Mark Ladd and Heinz-Peter Schlemmer. The researchers have pointed out that some questions about the new measuring method still have to be pursued. "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. "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."

Literatur:

Paech, Schuenke, Koehler, Windschuh, Mundiyanapurath, Bickelhaupt, Bonekamp, Bäumer, Bachert, Ladd, Bendszus, Wick, Unterberg, Schlemmer, Zaiss, Radbruch. T1ρ-weighted Dynamic Glucose Enhanced MRI in the Human Brain. Radiology 2017, DOI: 10.1148/radiol.2017162351

Website address: https://www.gesundheitsindustrie-bw.de/en/article/press-release/mri-without-contrast-agents-yes-with-sugar/