Nitroxide Compound CPTO-EG as an MRI Contrast Agent

Andrew Nencka¹, Xiping Liu¹, Joy Jeseph¹, Shi-Jiang Li¹, Balaraman Kalyanaraman¹

The conventional T1 contrast agent, gadolinium-DTPA complex, does not cross the blood brain barrier (BBB) in the absence of injury or tumor. Nitroxides possess a single unpaired electron but generally do not cross the BBB. The compound we developed can cross the BBB and provide MRI contrast in brain imaging by shortening the longitudinal relaxation time (T1) of water protons (1). Present study reports the progress of the development of a contrast agent, 2,2,5,5- tetramethylpyrroline 1-oxide 3-ethyleneglycolcarboxylate (CTPO-EG), which can cross the BBB and has significantly greater relaxivity.