The preclinical imaging market has changed so fast that the latest systems have completely transformed imaging to one compact, multi-modality system and done away with the need for liquid helium. This now means that where the MRI scanner was traditionally isolated in its own room, it no longer interferes with other technology in the laboratory due to the minimal stray magnetic field, and can be used safely in close proximity to other imaging modalities, such as X-ray CT, PET and SPECT. As a result MRI scanners can be placed in the laboratory, including class 3 and 4 laboratories.
To explain this, the ability to produce high resolution scans in MRI scanners is determined by the strength of the magnet (Teslas or Ts) which must be significant – high field – 3T or above. To achieve these high fields the magnet and wiring must be superconducting. This can only be accomplished by lowering the temperature to four degrees Kelvin (minus 269 centigrade). Traditionally this very low temperature was achieved by immersing the magnet in a bath of liquid helium – 200 litres or more -which resulted in a very large, heavy (many tonnes) and expensive scanner requiring its own special room with a Faraday cage incorporated into the walls.
Additionally provision has to be made for an emergency exhaust system. Should the magnet ‘quench’ (lose its superconductivity) the liquid helium turns to gas and expands 700 times. Without this safety provision there is a serious risk of asphyxiation to people in the vicinity.
The costs involved in purchasing this large and heavy scanner, incorporating the safety exhaust system, extensive building modifications and installation are very high and requires a lot of space which is at a premium in most laboratories.
The latest cryogen free, superconducting MRI systems from 3T to 7T are compact and can simply be wheeled through the door. This was achieved by eliminating the requirement for the expensive and cumbersome liquid helium jacket and safety exhaust provision by a revolutionary design which achieved the 4 degrees Kelvin through a patented wiring system and the use of an off the shelf cryo fridge unit. And because they have no cumbersome helium jacket an additional solenoid can be placed within the casing to reduce the stray magnetic field to a few centimeters allowing placement adjoining other sensitive equipment and scanners.
This radical redesign of the magnet and the resulting MRI systems has taken over three years with many iterations. Even today it requires great expertise and experience to build these new cryogen free, MRI systems and MR solutions is the only company to have successfully installed these advanced scanners.
The benchtop scanners have been further enhanced with innovative high-resolution PET and SPECT modules which can be added to create integrated multi-modality systems – either clipped on to the front or up the bore of the scanner. Multi-modality imaging is the use of two or more imaging methods to acquire data. Often one system will be used to acquire anatomical information and another to acquire functional information. By combining both anatomical and functional images it is possible to localize uptake of a tracer or contrast agent to a particular tissue or organ within a subject.
In a laboratory setting, multi-modality imaging is used to correlate genomic and phenomic types, make quantitative data more reliable, quantify the damage due to induced disease states or injuries and assess the usefulness of treatment options. Researchers can, for the first time, carry out independent imaging using the PET or SPECT modules, or sequential and simultaneous imaging with integrated PET or SPECT.
Where laboratories have old preclinical scanners, these can be upgraded to provide scanning capability to the standard of today’s updated MRI technology. The original magnet is refitted with new electronics and most importantly the spectrometer to the latest model which will provide superior soft tissue contrast and molecular imaging capabilities. As long as the magnet is intact the scanners can have a refit, depending on their Tesla power, to provide today’s scanning functionality. The cost of refitting varies but will always be far less expensive than buying a new preclinical machine.
The latest preclinical scanners have a number of additional capabilities including variable field of operation, higher intrinsic magnetic field homogeneity, larger fields of view (FOV), an elliptical shape to better fit the subject and automatic field ramping. Increased imaging performance has also been made possible by optimising the magnet performance.
MRI preclinical scanning technology can be used in an array of applications including neurobiological research, for instance brain imaging, epilepsy, spine imaging; cardiovascular research; embryology imaging to define development of the embryo; nephrology; full body imaging; organ imaging; morphological imaging; cancer research and a range of other applications. With improved imaging research can really be moved forward to improve health outcomes.
The preclinical imaging market is now at a particularly exciting stage with significant market growth, much of which is down to increased imaging capability thanks to multi-modality technology and a reduction in the cost. Further developments are coming on to the market all the time and this will help researchers to provide far better results. What’s next? Hopefully, the introduction of a higher strength cryogen free system in 2016 – the 9.4T is now in development – and more modalities incorporated into one scanner.