Cryogenics
for neuroimaging

Cryogenics
for neuroimaging

for CERMEP’s MEG imager

for CERMEP’s MEG imager

Magnetoencephalography

Magnetoencephalography

produits_ligne_30
produits_ligne_20

In September 2022, Absolut System supplied, delivered, installed, commissioned and trained a Helium purification and liquefaction system for the neuroimaging platform’s Magnetoencephalography (MEG) system at the Centre d’Exploration et de Recherche Médicales par Émission de Positons (CERMEP).

CERMEP’s MEG department offers the neuroscience community a non-invasive technique for functional exploration of the human brain. By definition, Magnetoencephalography (MEG) is a functional brain imaging technology that involves recording live, close to the head, the magnetic fields generated by the brain’s neurons. The cerebral magnetic field is around 1 billion times weaker than the earth’s magnetic field, so the imager is placed in an examination room (a Faraday cage-type shielded room) to avoid being subjected to potential external magnetic fields.

CERMEP’s MEG imager consists of a special cryostat, a helmet covering the subject’s head and 275 SQUIDS (Superconducting QUantum Interference Device) magnetic flux sensors, enabling measurements with excellent spatial resolution and sub-millisecond temporal resolution. To achieve sufficient measurement sensitivity, these sensors are immersed in liquid helium at 4.2K (-269°C), the temperature at which their superconducting capabilities can be expressed. The department is equipped for auditory, visual, tactile and electrical sensory stimulation.

Helium management
in closed loop

Helium management in closed loop

produits_ligne_40
produits_ligne_20

Helium evaporated by the MEG is collected in a low-pressure network
then compressed to 200 bars and stored in 600-liter spheres.

Helium evaporated by the MEG is collected in a low-pressure network
then compressed to 200 bars and stored in 600-liter spheres.

It is then expanded, purified, liquefied and stored in a 150-liter vacuum super-insulated tank (dewar) close to the MEG room, awaiting liquid transfer for top-up. The scrubber and liquefier installed use Pulse-Tube cryocoolers, offering high reliability, low maintenance and low vibration and noise levels. Helium liquefaction capacity was measured at 31 liters/day by Absolut System engineers, making CERMEP completely self-sufficient in helium management.

vase_projet_cermep
The proposed system consists of the following components:

Absolut System is able to supply a complete helium recovery system specially adapted to NMR cryomagnets, MRI or MEG medical systems or other systems for measuring magnetic or physical properties requiring helium.

Absolut System is able to supply a complete helium recovery system specially adapted to NMR cryomagnets, MRI or MEG medical systems or other systems for measuring magnetic or physical properties requiring helium.