Noninvasive brain imaging for experimental medicine in drug discovery

There is a widely shared perception that it is becoming increasingly urgent to find reliable measures related to therapeutic efficacy for use as early as possible in drug development. The inadequate understanding of diseases, limitations of animal models and difficulties in using their responses to anticipate drug effects in humans highlights the need to develop tools in experimental medicine to characterise human disease directly. Noninvasive imaging, particularly positron emission tomography and magnetic resonance imaging, provide a powerful range of methods for serial observation of drug distribution and interactions, and for assessing potential therapeutic mechanisms. Using imaging technology to establish biological proof-of-principle and as a pharmacodynamic marker for dose ranging would contribute greatly to the speed and efficiency of early decision making in new drug development. Imaging methods offer the ultimate promise for the development of clinically predictive surrogate markers of disease responses to new drugs.