Energy-dispersive x-ray microscopy to trace gadolinium in tissues.

An electron microscopic technique, energy-dispersive x-ray (EDX) analysis, was applied to rat tissue specimens containing gadolinium diethylenetriamine-pentaacetic acid (DTPA). EDX spectroscopy was able to detect the characteristic radiation spectra of gadolinium from tissues in concentrations as low as 0.005 mmol per gram of tissue. A mapping algorithm allowed the detected spectra to be assigned to a specific site of origin within the tissue. This technique allows direct visualization of the location of Gd-DTPA complexes in tissues.