6 By far the most commonly used PET ligands 18F-fluorodeoxyglucose (FDG), thanks to its availability and its excellent properties in oncological imaging. It is a tracer for glucose metabolism, and its

distribution is not specific to cancer cells but is also observed in inflammatory tissue, including macrophages, capillaries, and fibroblasts. FDG has been used to image inflammation processes and treatment monitoring in rheumatoid arthritis (Figure 1a),7–9 Inhibitors,research,lifescience,medical fever of undetermined origin (FUO), focal infection, musculoskeletal infections, sarcoidosis, and vasculitis.10 Figure 1 Examples of PET Imaging of Peripheral Pain Mechanisms. We have found that the tracer 11C-D-deprenyl provides excellent delineation of peripheral inflammatory sites, a method that holds potential

to elucidate the pathophysiological mechanism in chronic musculoskeletal pain disorders, including whiplash-associated disorder (Figure 1b)11 and rheumatoid arthritis.12 The translocator protein (18 kDa) has Inhibitors,research,lifescience,medical also been targeted to image peripheral inflammation in the lung,13 arterial Inhibitors,research,lifescience,medical walls,14 and intra-plaque inflammation in carotid atherosclerosis.15 Other peripheral inflammation probes, such as 68Ga peptides targeting vascular adhesion protein 1, are being developed (Figure 1c).16 The use of 68Ga is especially interesting as the nuclide emits Inhibitors,research,lifescience,medical positrons in high KU-0063794 supplier yields, it is readily chelated, and it is available as a generator product rather than from a cyclotron. The neurokinin-1 (NK1) receptor antagonist tracer 11C-”type”:”entrez-nucleotide”,”attrs”:”text”:”GR205171″,”term_id”:”238470896″,”term_text”:”GR205171″GR205171 used for CNS imaging was recently demonstrated to show elevated unilateral uptake in chronic tennis

elbow (Figure 1d).17 This finding suggests that NK1 receptors may be activated, or up-regulated in the peripheral, painful tissue of a chronic pain condition. The increased NK1 receptor availability is Inhibitors,research,lifescience,medical interpreted as part of ongoing neurogenic inflammation and may have correlation to the pathogenesis of chronic tennis elbow. IMAGING CENTRAL INFLAMMATION Dichloromethane dehalogenase Glia are the most abundant cells in the nervous system, and recent research has changed the perception of glia from being just supportive cells of neurons to being dynamic partners participating in brain metabolism and communication between neurons in health and in chronic pain.18–21 Astrocytes are the most abundant brain cell type in terms of their number and volume, and they constitute 40% to 50% of all glial cells. Astrocyte reaction has been demonstrated in peripheral nerve injury and in tissue inflammation models. Peripheral chronic nerve lesion is associated with breakdown of the blood–spinal cord barrier permeability and activation of astrocytes.