A method of measuring liquid flows in a living organism comprises the steps of applying an applied magnetic field to a living organism, introducing a time-varying quantity of a magnetizable fluid into a flow of liquid in the living organism, and measuring the variation in an induced magnetic field emanating from the living organism as a measure of the flow of the magnetizable fluid and the liquid within the living organism. The measurement of the induced magnetic field is preferably accomplished with at least two magnetic field sensors positioned at different locations relative to the living organism, whose outputs are detected with SQUID detectors. A cross correlation of the outputs of the magnetic field sensors permits the flow of liquid to be deduced as a function of time and location.