19F: A Versatile Reporter for Non-Invasive Physiology and Pharmacology Using Magnetic Resonance

The fluorine atom provides an exciting tool for diverse spectroscopic and imaging applications using Magnetic Resonance. The organic chemistry of fluorine is widely established and it can provide a stable moiety for interrogating many aspects of physiology and pharmacology in vivo. Strong NMR signal, minimal background signal and exquisite sensitivity to changes in the microenvironment have been exploited to design and apply diverse reporter molecules. Classes of agents are presented to investigate gene activity, pH, metal ion concentrations (e.g., Ca2+, Mg2+, Na+), oxygen tension, hypoxia, vascular flow and vascular volume. In addition to interrogating speciality reporter molecules, 19F NMR may be used to trace the fate of fluorinated drugs, such as chemotherapeutics (e.g., 5-fluorouracil, gemcitabine), anesthetics (e.g., isoflurane, methoxyflurane) and neuroleptics. NMR can provide useful information through multiple parameters, including chemical shift, scalar coupling, chemical exchange and relaxation processes (R1 and R2). Indeed, the large chemical shift range (∼ 300 ppm) can allow multiple agents to be examined, simultaneously, using NMR spectroscopy or chemical shift selective imaging.