Design of a mobile, homogeneous, and efficient electromagnet with a large field of view for neonatal low field MRI
ObjectiveIn 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 methodsThe 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.ResultsFunctionality 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) 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.ConclusionThe 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.
Magnetic Resonance Materials in Physics, Biology and Medicine