The low-field experts

• Siemens Healthineers employees Dr. Stephan Biber and Dr. David Grodzki, together with Prof. Michael Uder, Director of the Institute of Radiology, Uniklinikum Erlangen, Germany, have developed a new, innovative platform for magnetic resonance imaging (MRI) and integrated it into clinical routine. 
• Magnetom Free.Max and Magnetom Free.Star operate with a low field strength of 0.55 Tesla and enable MRI where it was not possible before.

Since the very first magnetic resonance imaging (MRI) examination was conducted in 1983, the only way has been up. Magnetic field strengths have increased, allowing for much clearer medical images and more accurate diagnoses. At the same time, however, higher field strengths have raised both the cost of this technology and its complexity. As a result, it is estimated that more than half of the world's population does not have access to this technology. That is why Dr. Stephan Biber and Dr. David Grodzki from Siemens Healthineers, together with Prof. Michael Uder, MD, Uniklinikum Erlangen, have developed a novel MRI platform that can operate at a field strength of 0.55 Tesla with excellent results. In doing so, the team has succeeded in breaking down barriers around the technology and enabling greater global access to MRI. 

MRI has revolutionized diagnostic imaging. In the case of rheumatism, for instance, it renders joint inflammation visible long before bone destruction can be detected on an X-ray. After a heart attack, an MRI scan can reliably determine where heart muscle can be saved by vascular surgery. In the case of liver tumors, it is possible to identify precisely healthy tissue that can be spared during surgery — and these are just a few examples of cases in which MRI facilitates reliable diagnoses that can improve therapy for patients. The procedure is particularly well suited for soft tissue imaging and is considered harmless to patients because it does not require radiation. 

Despite all these benefits, it is estimated that more than half of all people worldwide do not have access to MRI examinations. Cost is just one factor. Often the infrastructure to operate an MRI permanently is missing: This includes a stable power supply and the supply of liquid helium, both of which are needed to cool the magnet. In addition, the devices available to date are so large and heavy that they cannot be installed in many buildings at all, or only at considerable expense. Another reason is a lack of qualified personnel for the sometimes complex examinations. The limited space inside an MRI system also presents challenges for certain people, such as children or individuals who are claustrophobic or obese. 

About six years ago, a research team from Siemens Healthineers led by Stephan Biber and David Grodzki began to challenge the general consensus that high field strength is the only way forward in MRI. Their aim was to fundamentally rethink the technology to make it accessible to more people. The key requirement for the new platform was a lower magnetic field strength, which would reduce cost and complexity. Here, the challenge was to use a weaker magnetic field of 0.55 Tesla (T) to produce images with diagnostic quality comparable to that of conventional devices with field strengths of 1.5T and higher. However, lowering the field strength means that measurement times would have to be extended to obtain images of high diagnostic value. To solve this dilemma, new acquisition techniques and image reconstruction methods based on artificial intelligence (AI) were developed for the new system platform.

Closed helium cycle for sustainable magnet cooling 
Another crucial innovation concerns the cooling of the magnet. Helium, which is used as a liquid coolant, is not only expensive, but it is also a scarce resource in many parts of the world. To address these issues, for the new Magnetom Free.Max and Magnetom Free.Star systems the team around Biber and Grodzki developed an innovative magnet technology. It reduces the amount of liquid helium required from around 1,500 liters down to just 0.7 liters and allows it to be preserved in a closed circuit. This means that the new systems can be restarted automatically even after prolonged power failures without refilling the helium, as would be required with conventional MRI devices. 

Compact product design for easy installation 
Weighing in at just under three metric tons with a footprint of only 24 square meters, the new MRI systems can be operated in places where MRI was not an option in the past. They can even be installed in buildings with lower load-bearing floors and higher up in the building. In addition, the new systems can be transported through standard-sized doors of two meters in height and across existing corridors without having to remove doors and walls or even construct entirely new buildings. 

Enlarged bore size and ease of use 
By reducing the magnetic field strength, it was also possible to increase the bore size of Magnetom Free.Max to 80 centimeters, compared with 60 or 70 centimeters in earlier systems. This allows the system to accommodate claustrophobic and obese patients as well children, who can now better interact with their parents during the examination, while reducing the need for sedation. 

To simplify operation and thus address the shortage of skilled workers worldwide, a highly automated and simplified user interface was developed specifically for the new system platform. Therefore, a highly automated and simplified user interface has been developed especially for the innovative new system platform. It is designed to help prevent operating errors while automated algorithms are used to adapt the image acquisition to specific organs. 

A new class of magnetic resonance imaging systems 
Stephan Biber, David Grodzki and Michael Uder have developed and integrated into clinical routine a new class of MRI scanners that are already in widespread use two years after their market launch. Installations include hospitals in Brazil, India, Yemen, and Angola. The new systems have improved access to MRI in Germany, too. In the pediatric radiology department of Uniklinikum Erlangen, the compact design of the new system allowed it to be installed in a room near the intensive care unit to simplify patient exams. Technologies developed specifically for the MRI platform, such as AI-based image reconstruction, are already available for other MRI systems from Siemens Healthineers used in areas such as cardiac imaging and clinical research.

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