Unprecedented Resolution & Informative Play of Colors: New MRI Procedure and Light Field Microscopy Reveal Fine Structures and Connections in Mouse Brain Millions of Times Sharper Than Normal MRI, Paving the Way for Study of Neurodegenerative Diseases.

2023-04-20 16:57:11

Informative play of colors: This image shows the structures and connections in the brain of a mouse in unprecedented resolution – it is millions of times higher than in normal magnetic resonance imaging (MRI). By combining a new MRI procedure with light field microscopy, scientists can also visualize changes in certain brain areas and connections.

Magnetic resonance imaging (MRI) was invented almost exactly 50 years ago. With this method of fluoroscopy, strong magnetic fields cause atoms in the body tissues and especially in the water to vibrate. The radio waves generated by these vibrations are recorded by the MRI. Because every tissue reacts differently to the excitation, depending on its water content, shades of gray appear in the resulting image, which make the fine structures visible.

A high-resolution tomograph…

The image of a mouse brain shown here is from a new MRI method that allows for much higher resolution. Allan Johnson from Duke University and his team used a special tomograph that uses a 9.4 Tesla magnet and particularly powerful magnetic coils. “The resulting high angular resolution has enabled the most detailed maps of brain connectivity ever created,” the researchers explain.

Each three-dimensional pixel in the image is only around five micrometers in size. That’s millions of times sharper than current MRIs and 27,000 times sharper than the best MRI scanners used in research. This makes the fine structures of the mouse brain more visible than ever before.

…and a light field microscope

But that’s not all: After the researchers had created the MRI images of the mouse brain, they combined this with a special method of light field microscopy. The tissue is clarified, selectively stained for certain proteins and then imaged with a resolution of 1.8 micrometers per pixel. A special algorithm then combines this microscope image and the MRI images.

The result is an image in which the colors make certain cell types and brain connections recognizable, depending on the staining technique chosen. These composite images then make it possible, for example, to understand the changes in the brain that are typical of aging or the changes associated with neurodegenerative diseases such as Alzheimer’s. “That makes a big difference: We can now study such diseases in a completely new way,” says Johnson. (Proceedings of the National Academy of Sciences, 2023; dhi: 10.1073/pnas.2218617120)

Those: Duke University

20. April 2023

– Nadja Podbregar