How to Modulate Tumor Hypoxia for Preclinical In Vivo Imaging Research

Figure 2

The binding mechanism of 2-nitroimidazole tracers here represented as X-NO₂. (a) Under hypoxic conditions, tracer diffuses into the cell, where the NO₂ group undergoes a series of reductions and some of the intermediate products that are formed during these reactions will bind to macromolecules within the cell. (b) Under normoxic conditions, the first reduction is reversed, giving rise to the original compound which can unhinderedly exit the cell. Importantly, for removal of 2-nitroimodazole background signal, an uptake time of minimal 3 hours is needed [3].