A Room-Temperature Susceptometer to Measure Liver Iron: Susceptometer Design and Performance

摘要

We describe a biomagnetic susceptometer using room-temperature magnetic sensors instead of Superconducting QUantum Interference Devices (SQUIDs). By oscillating the magnetic field, canceling the applied-field signal, and modulating the sensor-patient distance, the room-temperature system resolves magnetic-susceptibility signals roughly 10{sup}8 times weaker than the applied magnetic field. The instrumental error, including both sensor noise with 80 seconds of data averaging and drifts over a 50-minute period, is approximately equivalent to the signal due to liver iron at a concentration of 28 micrograms per gram of wet tissue. Unlike earlier prototypes, the susceptometer samples approximately the same tissue volume as existing SQUID systems, so that errors due to the lung are expected to be no greater than in previous liver susceptometry. Planned measurements on human subjects will compare the room-temperature susceptometer with an existing SQUID system.