LOW FIELD MAGNETIC RESONANCE IMAGING WITH SQUIDS

SUPERCONDUCTING QUANTUM INTERFERENCE DEVICES (SQUIDS) ARE THE MOST SENSITIVE MAGNETIC FIELD DETECTORS IN EXISTENCE. RECENT EXPERIMENTS HAVE SHOWN THAT SQUIDS CAN BE USED TO DETECT RADIO FREQUENCY NUCLEAR MAGNETIC SIGNALS. THIS OPENS UP THE POSSIBILITY OF USING SQUIDS TO DO MAGNETIC RESONANCE IMAGING (MRI), PARTICULARLY AT LOW FIELDS. SQUID DETECTION WOULD MAKE POSSIBLE (1) INCREASED IMAGE CONTRAST USING VERY LOW APPLIED FIELDS, (2) ENHANCED SENSITIVITY FOR DETECTING NON-HYDROGEN NUCLEI, (3) SYSTEMS THAT OPERATE AT A WIDE RANGE OF FREQUENCIES, AND (4) LOW COST SYSTEMS USING INEXPENSIVE LOW FIELD MAGNETS. SQUID MRI SYSTEMS WILL BE COST EFFECTIVE WITH CONVENTIONAL LOW TC (CRITICAL TEMPERATURE) SQUIDS, AND WILL BE EVEN LESS EXPENSIVE AS GOOD HIGH TC SQUIDS BECOME AVAILABLE. IN PHASE I, A DESIGN FOR A PROTOTYPE IMAGING SYSTEM WILL BE SPECIFIED. PART OF THE PHASE I EFFORT WILL BE TO SHOW THAT SQUIDS CAN BE ADAPTED TO AN IMAGING ENVIRONMENT OF CHANGING FIELDS AND GRADIENTS.