Biomarkers for chronic pain and analgesia. Part 2: how, where, and what to look for using functional imaging.

Rapid advances in brain imaging chronic pain patients have yielded exciting data sets that could provide the basis for the development of chronic pain biomarkers that could increase the probability of success in analgesic drug development, aid clinicians in understanding, tracking, and treating disease, and link patients to the most effective therapies for their pain conditions. This review explores the potential of brain imaging techniques to detect functional, morphometric, and chemical changes that could serve as biomarkers for disease state and therapeutic efficacy. An important area for future research is to image clinical ongoing pain to further our knowledge of brain function in different pain states and the effects of treatment.