MAGNETIC-SUSCEPTIBILITY MAPPING OF THE HUMAN THORAX USING A SQUID BIOMAGNETOMETER

Biomagnetism is essentially the study of the weak magnetic fields gene rated by biological organisms, in particular the human body. The human thorax is composed of a variety of tissues and organs of slightly dif ferent magnetic susceptibility. In an applied magnetic field (of the o rder of milliTeslas) these small differences in susceptibility lead to measurable field variations (of the order of nanoTeslas) at the body surface which may be of diagnostic value. Physiological processes such as cardiac activity, cardiac output, blood flow and respiratory relat ed lung volume changes also contribute to the observed signal. In this study susceptibility 'maps' were obtained by measuring the magnetic f ield at several hundred points over the thorax. Results Indicate that magnetic susceptibility mapping produces low-resolution images of inte rnal body structures from which is should be possible to detect pathol ogies that cause alterations in tissue susceptibility.