Biomagnetic imaging.

Generation, transfer and reception of sensory information in the human body is established by electric events, a multitude of current pulses propagating electric events, a multitude of current pulses propagating through the nervous system and muscles. Today, medical diagnosis is based on recording the electric potentials created by these pulses--ECG or EEG--with electrodes on the skin or invasively with catheters. In addition, the magnetic field generated simultaneously allows a sufficiently precise localisation of single events as well as current trains. By fusion with three dimensional anatomic images, sources and propagation of electrical activity can be visualised in biomagnetic images with resolution in space as well as in time. These prospects resulted in a continuing interest in biomagnetism (BM) even though specific equipment for the detection of magnetic field patterns was not available. Technological progresses recently allowed systems containing many, integrated, highly sensitive sensors to be developed. These are quite large enough to cover the area over the human skull and heart. The registration of magnetic field patterns in one shot allows localisation of sporadic events and reduces the time for data acquisition to a few minutes. In addition to explaining the characteristics of BM fields and modern techniques for their registration this paper focuses on the results of pilot studies, performed during the last 2 years with multichannel systems. It was shown that sufficient correlation exists to normal physiology. Pathology was studied mainly in heart diseases and in epilepsy.