Abstract: There is provided an apparatus for using magnetic induction spectroscopy, MIS, to determine a measure of the fluid content of a tissue sample of a subject, the apparatus comprising a first excitation coil that is to be placed near to the tissue sample for inducing a current in the tissue sample; a reference coil; a second excitation coil that is arranged close to the reference coil and that is for inducing a current in the reference coil; and a control unit that is configured to apply an alternating current to the first excitation coil and the second excitation coil; obtain a measure of the current induced in the tissue sample; and determine a measure of the fluid content of the tissue sample from the measure of the current induced in the tissue sample.