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MIRCen facilities

MRI and PET imaging


The imaging platform provides equipment and expertise in the imaging of the central nervous system by nuclear magnetic resonance (NMR),positron emission tomography (PET) and optical imaging.
Published on 3 July 2018
Imagerie TEP, IRM et Optique


MRI facilities


PET and radiochemistry


Optical imaging


Nuclear magnetic resonance imaging of the central nervous system

Activities

High-resolution imaging techniques and multinuclear (13C and 31P) spectroscopy are being developed and validated with a 7T magnet:

  • Optimized NMR sequences for rodents and primates (T1, T2 and T2* weighting).
  • Optimized NMR sequences for 1H, 13C and 31P cerebral spectroscopy in rodents and primates, automated quantification of short-echo time spectra.
  • CEST imaging (« chemical exchange saturation transfer ») of the glutamate in rodents
  • Other sequences can be optimized in the framework of collaborative projects.


equipment

Examinations can be carried out on rodents and primates in biosafety level 1, 2 or 3 confinement. The magnet is sealed in a hermetic sarcophagus, making it possible to carry out maintenance interventions on the magnet in confinement conditions.

par-20091113-002_img_medium.jpg 
A magnetic resonance imaging experiment on the 11.7Tesla preclinical MRI machine at MIRCen (courtesy of P. Stroppa/CEA).

 

  • Horizontal 7T magnet/ 40 cm (Agilent)
  • Dedicated gradient for primates (internal diameter of 29 cm).
  • Dedicated gradient for rodents (internal diameter of 12 cm).
  • Radiofrequency coils optimized for the brain and spinal cord of primates and rodents.
  • Facilities for monitoring physiological parameters for primates and rodents, compatible with MRI.
  • Horizontal 11.7 T magnet (Bruker) for imaging in rodents (funded by NeuraTRIS) equipped with a cryoprobe.


PET and Radiochemistry

Activities

The expertise of MIRCen in the domain of PET imaging covers the following strategic axes:

1.  The validation of radiotracers in validated animal models of human diseases.

2.  The validation of animal models by PET with validated radiotracers.

​3.  The evaluation of new therapies with a view to transfer to clinical research.


The PET platform also works closely with the NMR and histology platforms for the three-dimensional reconstruction of multimodal images (Image Processing platform).


PET imaging system for rodents

equipment

The PET platform currently houses:

  • Two PET systems are available allowing two PET examinations to be carried out simultaneously for studies in rodents and primates (FOCUS 220, Siemens, Knoxville, TN). These two systems have the following characteristics: 

    • An axial field of view of 7.6 cm,
    • A transaxial field of view of 19 cm,
    • A spatial resolution of 1.4 mm,
    • A sensitivity of 3.4%
  • Two Swisstrace systems to automatically measure the input function of whole blood
  • Anesthesia and monitoring equipements for small animals
  • A lab dedicated to autoradiographic studies with long half-time isotopes

Radiochemistry

Activities

The radiochemistry platform allows the radiosynthesis and the development of new radiotracers specific to biological targets involved in a pathological process. Labeling concerns little molecules (molecular weight < 500 Da) and macromolecules (molecular weight > 500 Da) also. The future in house cyclotron will produce the 2 short half-life radioisotopes 11C and 18F (20.4 and 109.8 minutes respectively):

  • For [18F]fluorine labeling, nucleophilic reactions based on [18F]fluoride are used.
  • For [11C]carbon labeling, [11C]carbon dioxide is the primary precursor;  O- and N-methylation reactions (involving [11C]CH3I or [11C]CH3OTf) or carbonylation reactions are mainly used.

    Another radioisotope with a longer radioactive half-life will be used latter when the pharmacokinetics of the radiotracer and the biological process under study will require it.

    At the end of the radiosynthesis, all radiotracers are analyzed by HPLC in a quality control lab to check their chemistry and radiochemistry purities.

equipment

Since the opening of MIRCen, PET tracers have been radiolabeled at the Radiochemistry Laboratory of Frédéric Joliot Hospital, with a biomedical cyclotron and dedicated synthesizers housed in ventilated, shielded areas, according to current regulations. The future new radiochemistry infrastructure will make use of the same facilities.



​Cyclone 18/18 IBA cyclotron
​Lemer Pax hot cell



Flexlab iphase synthetizer



Optical imaging

ACTIVITIES

  • Biodistribution of macromolecules (aptamers, antibodies, peptides, nanoparticles)
  • In vivo monitoring of cell migration, differentiation and amplification
  • In vivo imaging of gene expression.

EQUIPMENT

  • A near-infrared fluorescence imaging system (fDOT) equipped with two lasers (680 and 740nm) allowing in vivo 3D quantitative imaging at a resolution of mm3..
  • A confocal fiber endo-microscopy system (pCLE) equipped with a 488nm laser and allowing the in vivo imaging of probes or fluorescent proteins at a resolution of a few microns.  


​Apparatus of fluorescent diffuse optical tomography (fDOT)
​Probe based confocal laser endomicroscopy (pCLE)