2-Nitroimidazole as Potential Nanoprobe in Hypoxia Imaging by MRI/PET

2-Nitroimidazole is radiosensitizer and serves as imaging contrast agent by 19F- and 31P MR methods. Despite the success of mesonidazole and SR-4554 compounds, very little is known of its hepato-cytotoxicity if it can be potential hypoxia imaging marker and non-toxic drug. Authors established the low oxygen, low energy metabolic ratio and gluconeogenesis in nitroimidazole induced hepatocytes and Kupffer cells leading to apoptosis'. Several new nanoparticles of nitroimidazole have emerged: nitroimidazole CI-1010, alginate-, silver-nanobullets as nanoparticles in imaging applications. Emerging 18F/19F double labeling techniques further give hope of MRI/PET imaging by using 18F/19F-FETNIM (erythronitroimidazole). Present art exists: 1. 18F/19F - 1 [2 fluoro-ethoxy-methyl- or - 1 [2 fluoro-hydroxymethyl-ethoxy-methyl-2- nitroimidazole can be choice of hypoxia MRI/PET imaging contrast agents; 2. availability of Hyoxyprobe(TM) and KU-2285 has enhanced the sensitivity of hypoxia quantitation; 3. copper labeled diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) selectively bind to hypoxic tumor cells. Cu-ATSM PET can be modality to image tumor hypoxia and contribute to the PET signal; 4. Improved compartment modeling analysis separates tumor tissue time-activity of nanoparticle signal into intravascular and extravascular components; 5. the dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), blood oxygen level dependent (BOLD) and FLOOD T2* imaging, and the measurement of lactate by MR methods serve as hypoxia surrogates and provide the pO(2) status of the tumor. The fusion of NMR and A PET images generates stereotactic marker template of tissue. In conclusion, nanoparticle enhanced multimodal MRI/PET diagnostic sensitivity serves hypoxia events better.