Abstract: The invention provides a specific measure of iron stores in vivo using magnetic resonance imaging. T.sub.2 relaxation times in both lower-to-mid field strength magnetic resonance imaging instruments and a higher field strength instrument is evaluated. T.sub.2 obtained at the higher field strength instrument is subtracted from T.sub.2 obtained at the lower field strength instrument. This difference, T, is then correlated with a quantitative measure of the iron stores in vivo in the scanned tissue. A two-dimensional or multidimensional map of the scanned tissue is then constructed on the basis of T to visually identify different tissue types as being normal or abnormal, either through a visual determination based on gray scales or a numeric comparison based on quantitative measure. The introduction of artificial or nonbiological substances as opposed to natural ferritin, is permitted for further diagnostic use by application of this methodology.