MRI Images Get 64 Million Times Sharper

Researchers have made a major breakthrough in the field of magnetic resonance imaging (MRI) by producing the sharpest-ever images of a mouse brain. MRI is an imaging technique used to visualise soft, watery tissue that is difficult to capture with X-rays. While MRI can identify a brain tumour, it has not been able to visualise microscopic details within the brain that reveal its organisation. The new high-resolution MRI was developed by the Duke Center for In Vivo Microscopy in collaboration with colleagues at the University of Tennessee Health Science Center, University of Pennsylvania, University of Pittsburgh and Indiana University.

The researchers generated scans of a mouse brain that are dramatically crisper than a typical clinical MRI for humans. The images are equivalent to going from a pixelated 8-bit graphic to the hyper-realistic detail of a Chuck Close painting. A single voxel of the new images, which can be thought of as a cubic pixel, measures just 5 microns, 64 million times smaller than a clinical MRI voxel.

This new MRI provides an important new way to visualise the connectivity of the entire brain at record-breaking resolution. Although the researchers focused their magnets on mice instead of humans, the refined MRI provides new insights that will lead to a better understanding of human conditions, such as how the brain changes with age, diet, or even with neurodegenerative diseases like Alzheimer’s.

The Duke Center for In Vivo Microscopy has been working on this research for nearly 40 years. Over this time, the researchers have refined many elements that, when combined, made the revolutionary MRI resolution possible. Some of the key ingredients include an incredibly powerful magnet, a special set of gradient coils that are 100 times stronger than those in a clinical MRI, and a high-performance computer equivalent to nearly 800 laptops all cranking away to image one brain.

After scanning the brain tissue, the researchers then use a complementary technique called light sheet microscopy, which gives them the ability to label specific groups of cells across the brain, such as dopamine-issuing cells to watch the progression of Parkinson’s disease. The team then maps the light sheet pictures, which give a highly accurate look at brain cells, onto the original MRI scan, which provides a vivid view of cells and circuits throughout the entire brain.

With this combined whole brain data imagery, researchers can now peer into the microscopic mysteries of the brain in ways never possible before. One set of MRI images shows how brain-wide connectivity changes as mice age, as well as how specific regions, like the memory-involved subiculum, change more than the rest of the mouse’s brain. Another set of images showcases a spool of rainbow-coloured brain connections that highlight the remarkable deterioration of neural networks in a mouse model of Alzheimer’s disease.

The researchers hope that by making the MRI an even higher-powered microscope, they can better understand mouse models of human diseases, such as Huntington’s disease, Alzheimer’s, and others. This could lead to a better understanding of how similar things function or go awry in people. The researchers believe that their work will enable them to investigate the effects of modest dietary and drug interventions on the brain during extended lifespans. The researchers are optimistic that their breakthroughs in understanding mouse brains will lead to new treatments and cures for diseases that affect humans.