Feasibility study of imaging a living murine tumor by electron paramagnetic resonance

An electron paramagnetic resonance image was measured for the first time from in vivo field gradient spectra of a living murine tumor (Cloudman S‐91 melanoma in the tail of a DBA‐2J mouse) using the paramagnetic nitroxide imaging agent 3‐carboxamido‐2,2,5,5‐tetramethylpyrroline‐l‐oxyl injected into the tail vein. The experiments were accomplished at L‐band frequency (1.55 GHz) with a single‐turn flat‐loop coil. A cross‐sectional image was obtained perpendicular to the tail axis, which clearly distinguished features to the submillimeter resolution level. © 1987 Academic Press, Inc.