FFC MRI AT LOW MAGNETIC FIELD HOMOGENEITY

ALEJANDRO SALVATORI; AGUSTIN ROMERO; ESTEBAN ANOARDO; GONZALO RODRIGUEZ; ALEXIS BERTÉ

Pisa

Conferencia; 11th Conference in Fast Field Cycling NMR Relaxometry; 2019

University of Pisa and ICCOM-CNR

The magnetic field homogeneity is an important aspect in magnetic resonance imaging (MRI). Field inhomogeneity causes distortions in both the geometry and intensity of the image [1]. The homogeneity in commercial MRI scanners is usually close to few ppm, a condition hardly achievable in fast field-cycling (FFC) NMR electromagnets (typically of the order or higher than 100 ppm). We have recently presented a FFC relaxometer with MRI capabilities [2]. Such an instrument turns ideal for the study and design of new physical and chemical contrasts agents for field-cycled MRI. A key aspect of the FFC-MRI relaxometer relays on its magnet homogeneity: there is a compromise between the ideal requirements for MRI experiments and the required performance of the power supply (surviving to a certain degree of inhomogeneity strongly reduces technical difficulties and costs). In this work we present the instrument prototype of own design, and focus the discussion on the magnetic field homogeneity. The electromagnet is a novel variable-geometry Notch-type coil [3]. The variable-geometry electromagnet endows it with magnetic field and homogeneity correction capabilities. The magnet was degraded to 4500ppm and after adjustment of the magnet´s geometry a maximal recovery up to 1400ppm was possible. We will show first results after implementing methods [4] to deal with such inhomogeneity that successfully conduced to images without distortions. The machine is currently in use for the design of new physical contrasts based in the low-field manipulation of the spin-system.