  The problem of determining a current density confined to a volume from
measurements of the magnetic field it produces exterior to that volume is known
to have non-unique solutions. To uniquely determine the current density, or the
non-silent components of it, additional spatial encoding of the electric
current is needed. In biological systems such as the brain and heart, which
generate electric current associated with normal function, a reliable means of
generating such additional encoding, on a spatial and temporal scale meaningful
to the study of such systems, would be a boon for research. This paper explores
a speculative method by which the required additional encoding might be
accomplished, on the time scale associated with the propagation of sound across
the volume of interest, by means of the application of a radially encoding
pulsed acoustic spherical wave.
