Ultra-High Resolution 7 Tesla Scanner Records Over 50 Times More Detail than Current 3T Scanners

By MedImaging International staff writers
Posted on 05 Dec 2023

Image: Innovative design has helped achieve a tenfold better resolution for functional MRI brain imaging (Photo courtesy of UC Berkeley)

Mental disorders significantly impact individuals, families, and society at large. Despite being fundamentally disorders of brain function, most mental disorders are currently diagnosed based on behavioral symptoms rather than functional measures. This approach is not ideal because various mental brain states can lead to identical behaviors. Neuroscientists need a more powerful magnetic resonance imaging (MRI) technology to map brain information representation with greater precision. An international endeavor to enhance MRI resolution for brain studies has now achieved a significant milestone with the development of an ultra-high resolution 7 Tesla scanner. This scanner boasts a resolution up to 10 times finer than existing 7T scanners and over 50 times more detailed than the 3T scanners predominantly used in hospitals. With this advancement, scientists can observe functional MRI (fMRI) features as small as 0.4 millimeters, a substantial improvement from the 2 to 3 millimeters resolution typical of standard 3T fMRIs.

Developed by researchers at UC Berkeley in California, USA, this next-generation 7T MRI scanner, referred to as NexGen 7T, promises to revolutionize neuroscience research. It will enable scientists to examine the neuronal circuits within various regions of the brain's neocortex and track signal propagation across different cortex areas during cognitive processes. This could uncover the roots of developmental disorders, potentially leading to enhanced diagnostic methods for brain disorders. By identifying new biomarkers, it might be possible to diagnose mental disorders more accurately and earlier, aiding in the selection of optimal therapies. The NexGen 7T's heightened spatial resolution allows researchers to focus on the activities of approximately 850 individual neurons within a single voxel, a drastic improvement from the 600,000 neurons detectable with standard hospital MRI technology.

Standard MRI scanners in hospitals typically utilize superconducting magnets generating a steady 3 Tesla magnetic field, about 90,000 times stronger than the Earth's magnetic field. These 3T scanners can resolve fMRI details to about 2 to 3 mm, which is insufficient to study the brain's microcircuits, measuring only about 0.5 mm across. fMRI, which highlights blood flow changes in arteries and veins, effectively differentiates between oxygen-rich blood in active brain regions and oxygen-depleted blood in less active areas. This functionality enables neuroscientists to identify brain regions involved in specific tasks. However, the 3 mm resolution of a 3T fMRI only allows the observation of larger veins and not the smaller ones indicative of microcircuit activity. The advanced NexGen 7T scanner will empower neuroscientists to precisely pinpoint activities within the thin cortical layers of the gray matter and the narrow column circuits organized perpendicular to these layers.

"The NexGen 7T scanner is a new tool that allows us to look at the brain circuitry underlying different diseases of the brain with higher spatial resolution in fMRI, diffusion and structural imaging, and therefore to perform human neuroscience research at higher granularity," said David Feinberg, the director of the project to build the scanner. "The ultra-high resolution scanner will allow research on underlying changes in brain circuitry in a multitude of brain disorders, including degenerative diseases, schizophrenia and developmental disorders, including autism spectrum disorder."

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