A new concept for fast field-cycling MRI and localized relaxometry

AGUSTIN ROMERO; GONZALO RODRIGUEZ; GABRIELA A. DOMINGUEZ; ALEXIS BERTÉ; ESTEBAN ANOARDO

Warsaw

Congreso; Euromar; 2017

Euromar

Field-cycling magnetic resonance imaging (MRI) has emerged as an alternative technique that allows to explode physical contrasts in a better way than conventional MRI [1]. Although severe technical problems must be faced to produce high-quality images, promising new applications of this technique can be envisioned in the fields of medicine and material science. MRI capabilities in a field-cycling apparatus also enables localized relaxometry studies in heterogeneous samples. Fast-switchable magnetic fields (a few milliseconds) are mostly welcomed, since this facilitates the extension of potential studies to systems having shorter relaxation times. In this context, we are working in the design of a fast field-cycling (FFC) MRI instrument potentially usable with smalls animals, particularly suitable for 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 was solved after calculating optimal coils matching the reduced available space within the FFC magnet [4]. Gradient pulses are amplified using Techron 8607 amplifiers. A specific probe was designed for a sample volume of 35cm3. The magnet is driven using a modified Stelar Spin Master power supply, while the RF and gradient pulses are generated using a SpinCore Radio Preocessor G board. Transmitter and receiver functions are operated from a Stelar Spinmaster console. A whole digital system (DIXITAL) is under development to replace the SpinCore board and the Stelar console. 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 and the 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-cycling NMR, J. Magn. Reson. 259: 216-224, 2015.[4]- A. J. Romero, G. A. Dominguez and E. Anoardo, Longitudinal gradient coils with enhanced radial uniformity in restricted diameter: Single-current and multiple-current approaches, J. Magn. Reson. 276: 69-77, 2017.