This paper describes multi-channel SQUID systems for biomagnetic measurement developed at KIT and Yokogawa. They are MEG systems, 24-ch systems for peripheral nerve measurement and 9-ch high spatial resolution system. A concept of calibration of the SQUID sensor array is introduced and discussed. Also discussed are noise performance of the system and crosstalk between sensors. Some examples of biomagnetic measurement are introduced using these systems, and their usefulness in the future is discussed.

Magnetospinography (MSG) is one of the most promising techniques to detect the nerve activity of spinal cords thanks to its noninvasiveness and high spatial/temporal resolutions. Multichannel superconducting quantum interference device (SQUID) MSG measurement systems optimized for supine subjects have been developed previously and employed in clinical applications in hospitals. Magnetic source analyses of MSG data based on spatial filter techniques reveal the transition of reconstructed current distributions adjacent to the spinal cord. The propagation of the neural signals was noninvasively visualized. The MSG measurements provide significant diagnostic information such as irregularities in the transitions of the reconstructed current distribution and/or considerable decreases in the current intensity at the lesion. Such functional imaging of the spinal cord in addition to conventional neurologic examinations and morphological imaging will be fairly effective in presurgical lesion localizations of the spinal cord.