NexGen 7T

Raising the bar on 7T MR: Ultrahigh-res scanner peers deeper

December 06, 2023
by John R. Fischer, Senior Reporter
Scientists at UC Berkeley have built a functional MR (fMR) scanner with ten times higher resolution than existing 7T systems — and over 50 times more than 3T systems.

The researchers say the scanner, called NexGen 7T, will allow them to assess neurological activity at deeper depths and track the flow of information throughout the brain and cortex, potentially making it easier to identify biomarkers for dementia, schizophrenia, developmental disorders, and neurological conditions.

NexGen 7T was designed in partnership with Siemens Healthineers, coil maker MR CoilTech Limited, and image pulse sequence designer Advanced MRI Technology (AMRIT) in California.

"Normally, MR is not fast enough at all to see the direction of the information being passed from one area of the brain to another," David Feinberg, the director of the project, acting professor at the Helen Wills Neuroscience Institute at UC Berkeley, and president of AMRIT, in a statement.

Whereas standard 3T systems allow users to see fMR images at two to three millimeters across, NexGen 7T’s higher resolution enables them to visualize structures at 0.4 millimeters across to view microcircuits, which are only 0.5 mm across.

Its capabilities may offer several advantages for neurological assessments:

How Alzheimer’s disease unfolds
The higher resolution could possibly allow scientists to understand how observed changes in tau and amyloid beta relate to one another and lead to memory loss.

How functional changes cause mental disorders
This includes dyslexia, autism, schizophrenia, and conditions caused by dementia and stroke, according to Jack Gallant, a UC Berkeley professor of psychology. "What we need is more powerful MR machines like this so that we can map, at high resolution, how information is represented in the brain.”

Reduce physiologic limiters
The "Impulse" gradient coil by Siemens Healthineers gives the scanner its higher resolution and allows gradient pulses to be turned on and off quicker to record signals faster. Much higher amplitude gradients can be used without stimulating the peripheral nerves in the body or stimulating the heart, which can limit the resolution and speed at which signals are recorded.

Distinguish small veins
Scientists can pinpoint activity within microcircuits, providing insight into how people see the world based on what is represented in the visual cortex.

Potential model for 11.7T MR scanners
Nicolas Boulant, a physicist visiting from the NeuroSpin project at the University of Paris in Saclay, hopes to use NexGen 7T’s gradient coils and other components to increase resolution in 11.7T MR scanners.

"The higher the magnetic field, the more difficult it is to really grab the potential promised by these higher-field MR scanners to see finer details in the human brain," he said. "You need all this peripheral equipment, which needs to be on steroids to meet those promises.”

NexGen 7T MR systems have ten times higher resolution than standard 7T scanners and over 50 times more than 3T ones.

In addition to its refined gradients, NexGen 7T has a 128-channel receiver system that replaces the standard 32 channels for higher signal-to-noise ratio, and higher parallel imaging acceleration for faster data acquisition to encode large image matrices. It also has new pulse sequences of precisely timed gradient pulses to rapidly achieve ultrahigh resolution.

The scanner was a rebuilt version of a 7T system installed at UC Berkeley in 2020, and the project was backed by $22 million in funding from UC Berkeley's chancellor's office and the Weill Neurohub, and Brain Research through Advancing Innovative Neurotechnologies (BRAIN). Other NexGen 7T brain scanners must be custom built from regular 7T scanners but should cost substantially less than the first.

“We will soon be able to understand the human brain organization better, which will give us a new view into disease processes and ultimately allow us to test new therapies,” said Feinberg.

The findings were published in Nature Methods.