Introduction

The global MRI market is expected to increase 16% by 2023 [1]. There is a distinct need to consider sustainability and circular economics during MRI system design and engineering. In addition, it is essential for clinical adoption for these “greener” systems to be robust over their longevity.The magnet of a modern MRI scanner includes around 4000 kg of copper, 450 kg of combined Niobium and Titanium and uses approximately 1000 Liters of Helium [2]. All these finite and depleting sources additionally require intensive processes for sourcing, purifying and shipping. The continued production of this MRI system configuration is unsustainable, and the high material demands may drive the cost of new scanners even higher.Once created, the “always-on” scanner uses on average 60 MWh/year [3] - equivalent to 6 US-households and roughly 50% of a hospital’s medical imaging energy consumption [4]. The healthcare costs of acquiring, siting and maintaining these machines can be obstructive to hospitals.

Solution

Low-field MRI can contribute to solving these material and cost demands. Moving to low-field systems can reduce the demands as follows: reduced Helium requirements, less material used for magnet windings, reduced energy demands, eased shipping demands, reduced material for room shielding, and reduced overall system footprint. These requirements may help to dramatically reduce system costs and even facilitate portability.Furthermore, low field system can leverage advances in imaging technology/computation, magnet hardware innovations, and favorable relaxivity conditions (shorter T1, longer T2*) to mitigate for the reduced signal-to-noise and retain diagnostic-quality imaging. This means that a “greener” low field system could perform robustly for many diagnostic imaging applications.

Results

Excitingly, low-field MRI already has a growing resurgence in the research and industrial community [5], with a range of approaches and applications targets.At the National Institutes of Health, we have demonstrated that when retaining high-performance gradients, we can generate high quality images and also recover signal-to-noise at low field using non-Cartesian acquisitions (Fig 1) [6].Similar field strength systems commercially available include Viewray’s 0.35T scanner (6) for image-guided therapy and Synaptive’s 0.5T head scanner [7]. Moreover, Sarracanie et al. [8] and the associated research groups at Massachusetts General Hospital and the company Hyperfine (9) have demonstrated brain imaging in a portable, cryogen-free, ultra-low field (6.5 mT) scanner, that can be powered by a wall outlet.

Conclusion

Systems with lower magnetic field strengths may reduce the environmental impact of MRI and could be combined with other engineering, efficiency and disposal solutions. Although these low field designs may not be suitable for all diagnostic imaging demands, all of these approaches towards lower field systems can pave the way towards both sustainable and accessible MRI.

Acknowledgements

No acknowledgement found.

References

[1] 24x7mag.com. Imaging Roundtable: Measuring the MRI Market. Retrieved from: https://www.24x7mag.com/medical-equipment/imaging-equipment/mri/imaging-roundtable-measuring-mri-market/[2] European Coordination Committee of the Radiological, Electromedical and Healthcare IT Industry (COCIR) (2019). MRI superconductor recycling Retrieved from https://www.cocir.org/fileadmin/6_Initiatives_SRI/Annual_forum/REG01543-001_COCIR_Niobium_recycling_report_V4.pdf[3] European Coordination Committee of the Radiological, Electromedical and Healthcare IT Industry (COCIR) (2015) . Self-regulatory initiative status report. Retrieved from https://www.cocir.org/fileadmin/6_Initiatives_SRI/SRI_Status_Report/SRI_Status_Report_2015_-_21_September_2016.pdf[4] Department of Energy (2016). Energy Savings Potential and RD&D Opportunities for Commercial Building Appliances (2015 Update). Retrieved from https://www.energy.gov/eere/buildings/downloads/energy-savings-potential-and-rdd-opportunities-commercial-building-0A. E. Campbell-Washburn, et al. Opportunities in interventional and diagnostic imaging using high-performance low field MRI. Radiology; 2019; 293: 384-393.J. P. Marques, et al. Low‐field MRI: An MR physics perspective. J Magn Reson Imaging 2019; 49(6): 1528–1542.[6] https://viewray.com/discover-mridian/[7] https://www.synaptivemedical.com/products/evry/[8] Sarracanie, M., LaPierre, C., Salameh, N. et al. Low-Cost High-Performance MRI. Sci Rep 2015; 5: doi:10.1038/srep15177.[9] https://www.hyperfine.io/portable-mri