10 patients with a clinical suspicion of at least 60% likelihood that low back pain arises from the lumbar facet joints will be recruited in clinic. The clinicians will rate the likelihood clinically of facet joint origin of pain and will assign a theoretical treatment plan based on initial clinical impression. They will indicate which facet joints, if any, they would refer for percutaneous treatment. The patients will undergo and FDG PET/MRI of the lumbar spine with IV gadolinium. The MRI signal change and enhancement of the lumbar facet joints will be graded by 2 radiologists blinded to the clinical data. The FDG PET scan activity of the facet joints will be graded by two nuclear medicine radiologists blinded to the clinical information. The clinicians will then be segmentally unblended to the imaging data as follows: 1. facet joints with high grade MRI signal change, 2. facet joints with any MRI signal change, 3. facet joints with high grade PET activity, and 4. facet joints with any PET activity. At each of these 4 steps, the clinician will indicate if this information would have the potential to alter clinical care (assuming that the imaging biomarker in question would be a surrogate for inflammation and pain) and if the information is concordant to the clinical impression. The clinical course of each patients will be followed for 1 year after undergoing the PET/MRI examination.