Magnetometry of injury currents from human nerve and muscle specimens using Superconducting Quantum Interferences Devices

Acute lesions of polarized membranes lead to slowly decaying (`near-DC') injury currents driven by the transmembrane resting potential gradient. Here we report the first recordings of injury-related near-DC magnetic fields from human nerve and muscle specimens in vitro using Superconducting Quantum Interference Devices (SQUIDs) operated in a conventional magnetically shielded room in a clinical environment. The specimen position was modulated sinusoidally beneath the sensor array by a non-magnetically fabricated scissors lift to improve the signal-to-noise ratio for near-DC fields. Depending on the specimen geometry the field patterns showed dipolar or quadrupolar aspects. The slow decay of human nerve and muscle injury currents was monitored for several hours from a distance of a few centimeters. Thus DC-magnetometry provides a sensitivity which might allow the remote detection of injury currents also in vivo.