Mixed sensors are at present competitive with classical tuned coils for
the detection of MRI signals on a very low field range. A very low field head MRI system is developed without pre-polarization technique nor
magnetic shielding room. Homogeneity of the system and gradients were
characterized. A homogeneity of 115 ppm was achieved in a quasi-open
configuration. Linearity of the gradients was verified. The amplitude of each gradient was 100 times lower
than at high field but sufficiently high to achieve a resolution of 2 mm x 2 mm x 2 mm.