Title :
Use of a DC SQUID receiver preamplifier in a low field MRI system
Author :
Seton, H.C. ; Bussell, D.M. ; Hutchison, J.M.S. ; Lurie, D.J.
Author_Institution :
Dept. of Biomed. Phys. & Bioeng., Aberdeen Univ., UK
fDate :
6/1/1995 12:00:00 AM
Abstract :
We have used tuned receiver coils coupled to a dc SQUID preamplifier in a small scale magnetic resonance imaging (MRI) system operating at 425 kHz (B/sub 0/=0.01 T). The coil and SQUID are cooled to 4.2 K in a modified biomagnetic cryostat. The modifications provide transparency to rf signals originating outside the cryostat while maintaining an acceptably low liquid helium boiloff rate. By applying negative feedback we have damped low loss, high Q-factor SQUID input circuits to achieve a useful imaging bandwidth of over 2 kHz.<>
Keywords :
SQUID magnetometers; biomedical NMR; preamplifiers; 0.01 T; 2 kHz; 4.2 K; 425 kHz; DC SQUID receiver preamplifier; Q-factor; RF signals; biomagnetic cryostat; damping; liquid helium boiloff rate; loss; low field MRI system; magnetic resonance imaging; negative feedback; tuned receiver coils; Biomagnetics; Coils; Couplings; Feedback circuits; Magnetic resonance imaging; Negative feedback; Preamplifiers; Q factor; SQUIDs;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
