Design of a mobile, homogeneous, and efficient electromagnet with a large field of view for neonatal low-field MRI
- 250 Downloads
In this work, a prototype of an effective electromagnet with a field-of-view (FoV) of 140 mm for neonatal head imaging is presented. The efficient implementation succeeded by exploiting the use of steel plates as a housing system. We achieved a compromise between large sample volumes, high homogeneity, high B0 field, low power consumption, light weight, simple fabrication, and conserved mobility without the necessity of a dedicated water cooling system.
Materials and methods
The entire magnetic resonance imaging (MRI) system (electromagnet, gradient system, transmit/receive coil, control system) is introduced and its unique features discussed. Furthermore, simulations using a numerical optimization algorithm for magnet and gradient system are presented.
Functionality and quality of this low-field scanner operating at 23 mT (generated with 500 W) is illustrated using spin-echo imaging (in-plane resolution 1.6 mm × 1.6 mm, slice thickness 5 mm, and signal-to-noise ratio (SNR) of 23 with a acquisition time of 29 min). B0 field-mapping measurements are presented to characterize the homogeneity of the magnet, and the B0 field limitations of 80 mT of the system are fully discussed.
The cryogen-free system presented here demonstrates that this electromagnet with a ferromagnetic housing can be optimized for MRI with an enhanced and homogeneous magnetic field. It offers an alternative to prepolarized MRI designs in both readout field strength and power use. There are multiple indications for the clinical medical application of such low-field devices.
KeywordsElectromagnet Neonatal MRI Structural steel housing Biplanar gradient system Low-field MRI
We thank Toni Drießle for helpful discussions and permanently valuable engineering inputs.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human or animal subjects.
- 13.Feynman R, Leighton R, Sands M (2006) The Feynman lectures on physics, vol II. Addison-Wesley, Reading. ISBN 0-8053-9047-2 (Chapter 37: Magnetic Materials)Google Scholar
- 28.Kartäusch R, Wintzheimer S, Ledwig M, Jakob PM, Fidler F (2011) Compact magnet design with significantly reduced eddy currents based on ferrite material. In: International conference on magnetic resonance microscopy (ICMRM), Beijing, China, p 202Google Scholar
- 30.Grafendorfer T, Conolly S, Sullivan C, Macovski A, Scott G (2005) Can Litz coils benefit SNR in remotely polarized MRI? In: Proceedings of the 13th annual meeting of ISMRM, Miami Beach, FL, USA, p 923Google Scholar
- 34.LaPierre C, Sarracanie M, Waddington DEJ, Rosen MS (2015) A single channel spiral volume coil for in vivo imaging of the whole human brain at 6.5 mT. In: Proceedings of the 23rd annual meeting of ISMRM, Toronto, ON, Canada, p 1793Google Scholar