A new concept for Fast Field-Cycling MRI and localized Relaxometry

AGUSTIN ROMERO; ALEXIS BERTE; GONZALO RODRIGUEZ; ESTEBAN ANOARDO; GABRIELA DOMINGUEZ

Warsaw

Congreso; EUROMAR2017; 2017

Euromar

Field-cycling magnetic resonance imaging (MRI) has emerged as an alternative technique that allows to explodephysical contrasts in a better way than conventional MRI [1]. Although severe technical problems must be faced toproduce high-quality images, promising new applications of this technique can be envisioned in the fields of medicineand material science. MRI capabilities in a field-cycling apparatus also enables localized relaxometry studies inheterogeneous samples. Fast-switchable magnetic fields (a few milliseconds) are mostly welcomed, since thisfacilitates the extension of potential studies to systems having shorter relaxation times. In this context, we are workingin the design of a fast field-cycling (FFC) MRI instrument potentially usable with smalls animals, particularly suitablefor the design of relaxation-enhancing contrasts agents, within other non-biomedical applications [2].The prototype system is based on a FFC magnet with variable geometry of own design [3]. The gradient unit wassolved after calculating optimal coils matching the reduced available space within the FFC magnet [4]. Gradient pulsesare amplified using Techron 8607 amplifiers. A specific probe was designed for a sample volume of 35cm3. Themagnet is driven using a modified Stelar Spin Master power supply, while the RF and gradient pulses are generatedusing a SpinCore Radio Preocessor G board. Transmitter and receiver functions are operated from a Stelar Spinmasterconsole. A whole digital system (DIXITAL) is under development to replace the SpinCore board and the Stelarconsole. In addition, a state of the art power supply is in progress.In this work we will discuss the need and limitations of the approach, and we will show details of the hardware andthe very first results.[1]- D. J. Lurie, S. Aime, S. Baroni, N. A. Booth, L. M. Broche, C.-H Choi, G. R. Davies, S. Ismail, D. hÒgáin and K.J. Pine, Fast field-cycling magnetic resonance imaging, C. R. Physique 11: 136-148, 2010.[2]- Funded by FONCyT (Argentina), projects 2013-1380 and 2013-2600.[3]- S. Kruber, G. Farrher and E. Anoardo, Air core notch-coil magnet with variable geometry for fast-field-cyclingNMR, J. Magn. Reson. 259: 216-224, 2015.[4]- A. J. Romero, G. A. Dominguez and E. Anoardo, Longitudinal gradient coils with enhanced radial uniformity inrestricted diameter: Single-current and multiple-current approaches, J. Magn. Reson. 276: 69-77, 2017.