Improving access to the gold standard of MRI scanning for earlier diagnosis and drug development
Siemens Magnet Technology (SMT), an Oxfordshire-based subsidiary of Siemens Healthcare UK, has developed a groundbreaking 7 tesla (7T) magnet which is at the heart of the first Magnetic Resonance Imaging (MRI) system suitable for both research and clinical applications. With more than double the field strength of most MRI scanners, the MAGNETOM Terra enables much higher resolution images. Siemens Healthcare will be seeking FDA and CE approval in the next year and, pending approval, it could help to achieve earlier diagnoses for neurological conditions such as Alzheimer’s, Parkinson’s and multiple sclerosis.
MRI scanners use strong magnetic fields and radio waves to produce detailed images of the inside of the body. They can be used to examine almost any part of the body, and the stronger the magnetic field, the higher the resolution of the images produced. The first MRI scanners, developed in the 1970s, had a magnetic field strength of well under 1.0 tesla. Today, most MRI scanners operate at 1.5 to 3.0 Tesla, and have become an invaluable diagnostic tool, used to help treat billions of patients around the world.
The Siemens ultra-high magnetic field (UHF) 7 tesla system delivers exquisite image quality to show vascularity of the brain without the need for an injection of contrast media often required at lower field strengths. This allows researchers to identify lesions and bleeds more easily, and the specific areas of the body affected - potentially enabling unprecedented insights into hard-to-diagnose conditions.
The MAGNETOM Terra could also assist in drug development through improved pre-screening of clinical trial participants to ensure their clinical conditions are similar, enabling more cost-efficient drug trials. It could also be used to help develop treatments for early stage diseases and enable monitoring of the efficacy of existing treatments, detecting, for example, whether chemotherapy drugs have penetrated a cancerous tumour.
Achieving such a jump in magnetic field was a huge engineering challenge. An MRI magnet is composed of a number of coils of thin wires carrying a very high current. The move from 3T to 7T required the addition of enough wire to stretch between London and Brussels. These coils then need to be cooled to 4.2 Kelvin (minus 269 Celsius) – the temperature of deep space – to enable the wire to become superconducting and carry enough current to generate a magnetic field 140,000 times that of the Earth’s magnetic field. The magnet is vacuum-insulated, like a thermos flask, in order to maintain the large temperature gradient between ambient conditions and -269°C around the inner magnet coils.
SMT’s system is less than half the weight of incumbent technologies and is pre-assembled and cooled at the factory ready for air freighting, unlike conventional ultra-high field MRI scanners, which have to be shipped in parts and assembled and cooled in situ. This saves several weeks and also cuts the helium requirement - a key advantage given the finite helium reserves on earth.
SMT, which employs 420 people at its Oxfordshire site, was able to achieve this step-change in MRI capability by starting from scratch rather than making incremental improvements to existing technologies. By investing heavily in R&D, and probing the absolute physical limits of the technology, the team completely re-invented the superconducting magnet, creating a smaller, lighter, better-integrated structure.
The team invented and patented a number of entirely new technologies that they are now using to improve the cost and accessibility of their mainstream MRI magnets. Just as Formula 1 technology pushes the boundaries of automotive technology but has subsequently ‘pulled up’ mainstream car technology, SMT’s 7T magnet technology has the potential to be deployed across the portfolio. SMT employed next-generation ‘lean engineering’ techniques and redesigned their factory to accommodate the 7T production line, moving 50% of the equipment in six months, with no impact on production of their existing products – whilst also keeping the new project secret. Such smart manufacturing helped them to win the 2015 Best Factory Award.
MacRobert Award judge, Professor David Delpy CBE FREng FRS FMedSci, said: “The Siemens team made a radical change from conventional wisdom in the development of the 7T and have achieved a step change in the manufacturability, reliability, performance and cost of MRI magnets, confirming their role as the world’s leader in this field. The result is a technology with the potential to save millions of lives through improved diagnostics and research techniques.”
Craig Marshall, Managing Director
Simon Calvert, Head of Product Innovation and Development and Chief Technology Officer
Matthew Longfield, Project Manager
Graham Hutton, Principle Magnet Engineer
John Laister, Head of Manufacturing