RESUMEN
We report dissolution Dynamic Nuclear Polarization (d-DNP) of [15 N3 ]metronidazole ([15 N3 ]MNZ) for the first time. Metronidazole is a clinically approved antibiotic, which can be potentially employed as a hypoxia-sensing molecular probe using 15 N hyperpolarized (HP) nucleus. The DNP process is very efficient for [15 N3 ]MNZ with an exponential build-up constant of 13.8â min using trityl radical. After dissolution and sample transfer to a nearby 4.7â T Magnetic Resonance Imaging scanner, HP [15 N3 ]MNZ lasted remarkably long with T1 values up to 343â s and 15 N polarizations up to 6.4 %. A time series of HP [15 N3 ]MNZ images was acquired in vitro using a steady state free precession sequence on the 15 NO2 peak. The signal lasted over 13â min with notably long T2 of 20.5â s. HP [15 N3 ]MNZ was injected in the tail vein of a healthy rat, and dynamic spectroscopy was performed over the rat brain. The in vivo HP 15 N signals persisted over 70â s, demonstrating an unprecedented opportunity for in vivo studies.