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Life Science Div./ Technology platforms/ In vivo imaging platforms/ NeuroSpin/ NeuroSpin - Very high field magnetic resonance

NeuroSpin - Very high field magnetic resonance

Biomedical imaging still comes up against a certain number of technical constraints that limit its potential: the current resolution in space (millimeters) greatly exceeds the size of the neurons, the functional units underlying brain activity; the temporal resolution is generally close to the second when the millisecond would be more representative of the processes involved; the parameters visualised (such as blood flow) only indirectly reflect the functioning of the neurons.

To overcome these obstacles and push the current limits in imaging as far as possible, CEA has decided to build a technical platform where unequalled imaging tools will be developed and used. Nuclear magnetic resonance (NMR) has been chosen as the privileged physics modality. NMR is based on the magnetic properties of the nuclei of atoms. It uses a magnet with a high and homogenous magnetic field, as well as specialized electronic and computer equipment.

NMR provides access to a great many different molecules and physical parameters in a non-invasive manner and without the use of radioactive isotopes. Measuring very low tissue magnetisation, NMR can be used to obtain a very precise, tridimensional view of deep organs. The greater the magnetic field, the higher the sensitivity, and the higher the spatial or temporal resolution that can be achieved.
Most NMR imaging systems (or MRI) currently installed in hospitals operate with magnetic fields that do not exceed 1.5 T*. The development of more ambitious research protocols requires apparatus with a higher field (>3 T). Recently, very high field devices operating at 7 or 8 T for studies on man have been developed in the U.S.A. Magnets with high and homogenous magnetic fields are at the heart of the NMR apparatus developed. They are made of superconducting wires cooled in liquid helium.
"Turnkey systems" operating at 4.7 T and 9.4 T already exist for animal studies. They are used for quasi-industrial biological or pharmacological applications. Even more efficient systems are available with 11 T or even 17 T magnets with diameters ranging from 10 to 40 cm. For human applications, the design of magnets capable of the utmost field intensity, beyond 10 T, on diameters close to 1 m remain a technological challenge.
Facing this technological challenge, NeuroSpin will be equipped with several types of intense field nuclear magnetic resonance (NMR) imaging units:

- A 3 T system for clinical trials (normal subjects and patients),
- Two high field systems (>10 T) for pre-clinical and clinical trials,
- A very high field system (>17 T) dedicated to small animals (mouse).

(*) the tesla is the magnetic field unit: the terrestrial magnetic field in Paris is 0.00005 tesla.

The know-how in the design of those magnets is also a specificity of CEA (Matter Sciences Division) which already contributes to the equipment of particle accelerators at CERN and the creation of associated detectors.

Together and in synergy, they will develop the tools and models required to push back the limits of imaging in the exploration of the brain as far as possible. These methodologies will help better understand the workings of the human brain as well as its anomalies during development and dysfunction.

  
 
3D display from MRI images
of the motor cortex and central structures as well as their connections.
 
 The original aspect of NeuroSpin is to bring together top-level methodologists and neurobiologists in the same place. 
 

Photos: CEA, Inserm, CEA/C, Dupont, CEA/L, Médard, CEA/M, Grassi, Inserm/Lachapelle, AP-HP/Inserm/CEA