Use of positron emission tomography to measure brain activity responses to fentanyl analgesia

This review illustrates the potential of positron emission tomography (PET) in elucidating the supraspinal analgesic mechanisms of opioids in humans. First, a range of PET methodologies, available for functional brain mapping both on the receptor and neuronal network level in humans, is examined briefly. Subsequently, studies that have taken advantage of only a small portion of these PET techniques are reviewed. In light of the limitations of these experiments, a series of strategies is discussed that, by exploiting the full arsenal of PET techniques, could provide unique insights into the supraspinal mechanisms of opioid analgesia under the clinically most relevant circumstances—in the living human brain.