Free radical imaging by electron spin resonance computed tomography in rat brain.

Images of nitroxide radicals were obtained from the brains of living rats following intracarotid injection of imaging agent, [2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinylox y] (16 DS) using L-band electron spin resonance computed tomography (ESR-CT). The image patterns obtained from the 3-carbamoyl-2,2,5,5-tetramethyl-1-pyrrolinyloxy injected rats showed the agent in tissues of the cranium but not within the brain. The uptake of 16 DS was found in the cortex, hippocampus, striatum, midbrain, pons medulla oblongata and cerebellum, and nuclei, mitochondria, synaptosomes of the cerebrum after intracarotid injection of 16 DS using an x-band ESR spectrometer. These results suggest that 16 DS penetrates the blood brain barrier.