New X-ray method for understanding brain disorders better

Researchers including members from the Niels Bohr Institute at the University of Copenhagen have developed a new method for making detailed X-ray images of brain cells. The method, called SAXS-CT, can map the myelin sheaths of nerve cells, which are important for conditions such as multiple sclerosis and Alzheimer's disease. The results have been published in the scientific journal, NeuroImage.

The myelin sheaths of nerve cells are lamellar membranes surrounding the neuronal axons. The myelin layers are important to the central nervous system as they ensure the rapid and uninterrupted communication of signals along the neuronal axons. Changes in the myelin layers are associated with a number of neurodegenerative disorders such as cerebral malaria, multiple sclerosis, and Alzheimer's disease.

The development of these diseases are still not fully understood, but are thought to be related to the damage of the myelin layers, so that messages from the brain reach the various parts of the body poorly or not at all. It is like an electric cord where the insulating material has been damaged and the current short circuits. In order to find methods to prevent or treat the diseases it is important to understand the connection between the diseases and the changes in the myelin.

Getting 3-D X-ray images

"We have combined two well-known medical examination methods: SAXS (Small-Angle X-ray Scattering) and CT-scanning (computed tomography scanning). Combined with a specially developed programme for data processing, we have been able to examine the variations of the myelin sheaths in a rat brain all the way down to the molecular level without surgery", explains PhD Torben Haugaard Jensen, Niels Bohr Institute at the University of Copenhagen. The method is called 'Molecular X-ray CT', because you use X-ray CT to study myelin at the molecular level.

The research has been carried out in collaboration with researchers in Switzerland, France and Germany. The experiments took place at the Paul Scherrer Institute in Switzerland, where they have a powerful X-ray source that can measure Small-Angle X-Ray Scattering, SAXS at a high resolution. Normally such experiments would give two-dimensional X-ray images that are sharp and precise, but without information on depth. But by incorporating the method from CT-scanning, where you image from different angles, the researchers have managed to get 3D X-ray images.

This has not only required the development of new X-ray methods and experiments, but has also required the development of new methods for processing data. The extremely detailed measurements of cross sections from different angles meant that there were 800,000 images to be analysed. So the researchers have also developed an image-processing programme for the SAXS-CT method. The result is that they can see all of the detailed information from SAXS in spatially resolved.

From point samples to total samples