Design of a mobile, homogeneous, and efficient electromagnet with a large field of view for neonatal low-field MRI

作者：Lother Steffen^*; Schiff Steven J; Neuberger Thomas; Jakob Peter M; Fidler Florian

来源：Magnetic Resonance Materials in Physics Biology and Medicine, 2016, 29(4): 691-698.

DOI：10.1007/s10334-016-0525-8

• Electromagnet
• Neonatal MRI
• Structural steel housing
• Biplanar gradient system
• Low-field MRI

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 B-0 field, low power consumption, light weight, simple fabrication, and conserved mobility without the necessity of a dedicated water cooling system.
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 x 1.6 mm, slice thickness 5 mm, and signal-to-noise ratio (SNR) of 23 with a acquisition time of 29 min). B-0 field-mapping measurements are presented to characterize the homogeneity of the magnet, and the B-0 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.

• 出版日期2016-8