Fluorine magnetic resonance in vivo: a powerful tool in the study of drug distribution and metabolism.

Magnetic resonance (MR) provides an attractive non-invasive way of studying drug distribution in vivo. Widespread occurrence of fluorine in medicinal compounds, and its favourable MR properties, make it an effective probe for drug absorption, distribution, metabolism and excretion (ADME) studies. We discuss practicalities of detection and localization, and when (19)F MR would add value in a clinical trial, exemplified by deployments in oncology and psychiatry, where it is a practical way of demonstrating chronic brain accumulation directly. Limitations are emphasized to minimize failure risk, for example, inadequate sensitivity relative to tissue drug concentrations. The review anticipates increasing clinical (19)F MR as high field human scanners become widespread, and requirements to demonstrate mechanisms underlying clinical effects become more pressing.