An imaging agent and a method of its use for imaging a necrosis in a tissue of a subject. The imaging method may be positron emission tomography (PET). In at least one embodiment the imaging agent comprises 2-deoxy-2-[18F]fluoroglucaric acid (18F-FGA), or a pharmaceutically-acceptable salt thereof. The imaging agent may be disposed in a pharmaceutically-acceptable excipient, carrier, diluent, or vehicle. The imaging agent may be contained within a kit. The disclosure includes in at least one embodiment a method of preparing a radiopharmaceutical such as 18F-FGA for use in imaging.