Use of PET/MR Imaging in Chronic Pain

The diagnosis and management of chronic and neuropathic pain syndromes remains a major clinical challenge, and this failure is partly attributed to our inability to identify the hypersensitive and inflammatory changes in the pain-sensing part of our nervous system that is thought to contribute to these syndromes. The lack of a specific, objective diagnostic test for chronic and neuropathic pain syndromes can result in a delay of diagnosis and suboptimal management decisions. This delay in diagnosis is quite unfortunate since the early diagnosis and treatment of a disease is attributed to the highest probability of remission in certain chronic pain syndromes. Additionally, identifying the correct source of pain is of paramount importance since the clinical course and therapeutic interventions are different depending on cause. Evidence in the literature points strongly toward an active inflammatory component in chronic pain. For example, soft tissue and bony inflammation is known to be an important pathophysiological mechanism for the symptoms of certain neuropathic pain syndromes. Similarly, individuals suffering from chronic sciatica or radiculopathy may suffer from a combination of inflammation and compression of lumbar or cervical spinal nerves. It is also established that inflammatory lesions have increased metabolism and energy requirements and, therefore, are more glucose-avid than normal tissues, showing increased uptake of radiolabeled glucose analogs, such as \[18F\]fluorodeoxyglucose (\[18F\]FDG). Correspondingly, \[18F\]FDG positron emission tomography-magnetic resonance imaging (PET/MRI) represent leading FDA-approved clinical imaging modalities to longitudinally study metabolic changes in the nervous system and non-neural tissues (e.g., muscle, blood vessels, joints, bone, scar tissue, etc.) in patients with chronic pain conditions. One of the goals of the study is to determine whether \[18F\]FDG PET/MRI can identify sources of inflammation with greater sensitivity, accuracy and objectivity than current diagnostic methods.