Magnetopneumography

Abstract

One of the earliest applications of biomagnetic techniques was to in vivo studies of the deposition and clearance of inhaled magnetic particles that lodged in the human lungs, a technique now known as “magnetopneumography.” Workers in certain occupations are exposed to dust having a sufficiently high concentration of iron oxides or other magnetic materials to produce a detectable remanent magnetic field outside the chest, once the lungs are subjected to a sufficiently strong field to magnetize the particles. Thus, measurements of the pattern of the remanent field over the chest provide information concerning the distribution of the dust in the lungs. Repeated measurements over the course of weeks and months is a gauge of the rate of clearance of the dust, or of its translocation from one place to another. Also of interest are studies of the “relaxation” of the remanent field once the magnetizing field is removed. This short-term effect appears to be a noninvasive technique for investigating dynamic aspects of the local environment of the particles in the lungs.