Biomagnetic susceptometer with SQUID instrumentation

A novel SQUID magnetometer for noninvasive measurements of hepatic (liver) iron stores is discussed. Placement of the SQUID, detection coil, and magnet in the dewar vacuum region significantly reduced system noise. In addition, the system incorporates multiple magnets and detection coils which may allow the discrimination of the surface skin layer from the deeper (weaker signal) true liver iron concentration. Measurements indicate an instrumental noise level that is <20 mu g/g of equivalent iron concentration.